Merge branch 'rw/make-needs-librt'

Makefile assumed that -lrt is always available on platforms that
want to use clock_gettime() and CLOCK_MONOTONIC, which is not a
case for recent Mac OS X.  The necessary symbols are often found in
libc on many modern systems and having -lrt on the command line, as
long as the library exists, had no effect, but when the platform
removes librt.a that is a different matter--having -lrt will break
the linkage.

This change could be seen as a regression for those who do need to
specify -lrt, as they now specifically ask for NEEDS_LIBRT when
building. Hopefully they are in the minority these days.

* rw/make-needs-librt:
config.mak.uname: define NEEDS_LIBRT under Linux, for now
Makefile: add NEEDS_LIBRT to optionally link with librt

diff --combined Makefile
index bfe85595cd0877924aa3cd3dca7b24ab17945d83,949925e9465314c96f85ea3b2bd5d128108fef53..1978cb8d40b578648c05fbcfd783f9dbf2178abb
--- 1/Makefile
--- 2/Makefile
+++ b/Makefile
@@@ -351,9 -351,12 +351,12 @@@ all:
  # Define GMTIME_UNRELIABLE_ERRORS if your gmtime() function does not
  # return NULL when it receives a bogus time_t.
  #
- # Define HAVE_CLOCK_GETTIME if your platform has clock_gettime in librt.
+ # Define HAVE_CLOCK_GETTIME if your platform has clock_gettime.
  #
- # Define HAVE_CLOCK_MONOTONIC if your platform has CLOCK_MONOTONIC in librt.
+ # Define HAVE_CLOCK_MONOTONIC if your platform has CLOCK_MONOTONIC.
+ #
+ # Define NEEDS_LIBRT if your platform requires linking with librt (glibc version
+ # before 2.17) for clock_gettime and CLOCK_MONOTONIC.
  #
  # Define USE_PARENS_AROUND_GETTEXT_N to "yes" if your compiler happily
  # compiles the following initialization:
@@@ -375,7 -378,13 +378,7 @@@ GIT-VERSION-FILE: FORC
  # CFLAGS and LDFLAGS are for the users to override from the command line.
  
  CFLAGS = -g -O2 -Wall
 -LDFLAGS =
 -ALL_CFLAGS = $(CPPFLAGS) $(CFLAGS)
 -ALL_LDFLAGS = $(LDFLAGS)
 -STRIP ?= strip
 -
 -ifdef DEVELOPER
 -CFLAGS += -Werror \
 +DEVELOPER_CFLAGS = -Werror \
        -Wdeclaration-after-statement \
        -Wno-format-zero-length \
        -Wold-style-definition \
@@@ -384,10 -393,7 +387,10 @@@
        -Wstrict-prototypes \
        -Wunused \
        -Wvla
 -endif
 +LDFLAGS =
 +ALL_CFLAGS = $(CPPFLAGS) $(CFLAGS)
 +ALL_LDFLAGS = $(LDFLAGS)
 +STRIP ?= strip
  
  # Create as necessary, replace existing, make ranlib unneeded.
  ARFLAGS = rcs
@@@ -437,6 -443,7 +440,6 @@@ DIFF = dif
  TAR = tar
  FIND = find
  INSTALL = install
 -RPMBUILD = rpmbuild
  TCL_PATH = tclsh
  TCLTK_PATH = wish
  XGETTEXT = xgettext
@@@ -617,7 -624,7 +620,7 @@@ TEST_PROGRAMS_NEED_X += test-svn-f
  TEST_PROGRAMS_NEED_X += test-urlmatch-normalization
  TEST_PROGRAMS_NEED_X += test-wildmatch
  
 -TEST_PROGRAMS = $(patsubst %,%$X,$(TEST_PROGRAMS_NEED_X))
 +TEST_PROGRAMS = $(patsubst %,t/helper/%$X,$(TEST_PROGRAMS_NEED_X))
  
  # List built-in command $C whose implementation cmd_$C() is not in
  # builtin/$C.o but is linked in as part of some other command.
@@@ -718,7 -725,6 +721,7 @@@ LIB_OBJS += diff-lib.
  LIB_OBJS += diff-no-index.o
  LIB_OBJS += diff.o
  LIB_OBJS += dir.o
 +LIB_OBJS += dir-iterator.o
  LIB_OBJS += editor.o
  LIB_OBJS += entry.o
  LIB_OBJS += environment.o
@@@ -783,7 -789,6 +786,7 @@@ LIB_OBJS += read-cache.
  LIB_OBJS += reflog-walk.o
  LIB_OBJS += refs.o
  LIB_OBJS += refs/files-backend.o
 +LIB_OBJS += refs/iterator.o
  LIB_OBJS += ref-filter.o
  LIB_OBJS += remote.o
  LIB_OBJS += replace_object.o
@@@ -941,7 -946,7 +944,7 @@@ BUILTIN_OBJS += builtin/verify-tag.
  BUILTIN_OBJS += builtin/worktree.o
  BUILTIN_OBJS += builtin/write-tree.o
  
 -GITLIBS = $(LIB_FILE) $(XDIFF_LIB)
 +GITLIBS = common-main.o $(LIB_FILE) $(XDIFF_LIB)
  EXTLIBS =
  
  GIT_USER_AGENT = git/$(GIT_VERSION)
@@@ -950,10 -955,6 +953,10 @@@ include config.mak.unam
  -include config.mak.autogen
  -include config.mak
  
 +ifdef DEVELOPER
 +CFLAGS += $(DEVELOPER_CFLAGS)
 +endif
 +
  ifndef sysconfdir
  ifeq ($(prefix),/usr)
  sysconfdir = /etc
@@@ -1467,13 -1468,16 +1470,16 @@@ endi
  
  ifdef HAVE_CLOCK_GETTIME
        BASIC_CFLAGS += -DHAVE_CLOCK_GETTIME
-       EXTLIBS += -lrt
  endif
  
  ifdef HAVE_CLOCK_MONOTONIC
        BASIC_CFLAGS += -DHAVE_CLOCK_MONOTONIC
  endif
  
+ ifdef NEEDS_LIBRT
+       EXTLIBS += -lrt
+ endif
+ 
  ifdef HAVE_BSD_SYSCTL
        BASIC_CFLAGS += -DHAVE_BSD_SYSCTL
  endif
@@@ -1574,15 -1578,7 +1580,15 @@@ TCLTK_PATH_SQ = $(subst ','\'',$(TCLTK_
  DIFF_SQ = $(subst ','\'',$(DIFF))
  PERLLIB_EXTRA_SQ = $(subst ','\'',$(PERLLIB_EXTRA))
  
 -LIBS = $(GITLIBS) $(EXTLIBS)
 +# We must filter out any object files from $(GITLIBS),
 +# as it is typically used like:
 +#
 +#   foo: foo.o $(GITLIBS)
 +#     $(CC) $(filter %.o,$^) $(LIBS)
 +#
 +# where we use it as a dependency. Since we also pull object files
 +# from the dependency list, that would make each entry appear twice.
 +LIBS = $(filter-out %.o, $(GITLIBS)) $(EXTLIBS)
  
  BASIC_CFLAGS += -DSHA1_HEADER='$(SHA1_HEADER_SQ)' \
        $(COMPAT_CFLAGS)
@@@ -1718,8 -1714,8 +1724,8 @@@ git.sp git.s git.o: EXTRA_CPPFLAGS = 
        '-DGIT_INFO_PATH="$(infodir_relative_SQ)"'
  
  git$X: git.o GIT-LDFLAGS $(BUILTIN_OBJS) $(GITLIBS)
 -      $(QUIET_LINK)$(CC) $(ALL_CFLAGS) -o $@ $(ALL_LDFLAGS) git.o \
 -              $(BUILTIN_OBJS) $(LIBS)
 +      $(QUIET_LINK)$(CC) $(ALL_CFLAGS) -o $@ $(ALL_LDFLAGS) \
 +              $(filter %.o,$^) $(LIBS)
  
  help.sp help.s help.o: common-cmds.h
  
@@@ -1908,11 -1904,10 +1914,11 @@@ VCSSVN_OBJS += vcs-svn/fast_export.
  VCSSVN_OBJS += vcs-svn/svndiff.o
  VCSSVN_OBJS += vcs-svn/svndump.o
  
 -TEST_OBJS := $(patsubst test-%$X,test-%.o,$(TEST_PROGRAMS))
 +TEST_OBJS := $(patsubst %$X,%.o,$(TEST_PROGRAMS))
  OBJECTS := $(LIB_OBJS) $(BUILTIN_OBJS) $(PROGRAM_OBJS) $(TEST_OBJS) \
        $(XDIFF_OBJS) \
        $(VCSSVN_OBJS) \
 +      common-main.o \
        git.o
  ifndef NO_CURL
        OBJECTS += http.o http-walker.o remote-curl.o
@@@ -2074,10 -2069,7 +2080,10 @@@ XGETTEXT_FLAGS_SH = $(XGETTEXT_FLAGS) -
        --keyword=gettextln --keyword=eval_gettextln
  XGETTEXT_FLAGS_PERL = $(XGETTEXT_FLAGS) --keyword=__ --language=Perl
  LOCALIZED_C = $(C_OBJ:o=c) $(LIB_H) $(GENERATED_H)
 -LOCALIZED_SH = $(SCRIPT_SH) git-parse-remote.sh
 +LOCALIZED_SH = $(SCRIPT_SH)
 +LOCALIZED_SH += git-parse-remote.sh
 +LOCALIZED_SH += git-rebase--interactive.sh
 +LOCALIZED_SH += git-sh-setup.sh
  LOCALIZED_PERL = $(SCRIPT_PERL)
  
  ifdef XGETTEXT_INCLUDE_TESTS
@@@ -2219,7 -2211,7 +2225,7 @@@ bin-wrappers/%: wrap-for-bin.s
        @mkdir -p bin-wrappers
        $(QUIET_GEN)sed -e '1s|#!.*/sh|#!$(SHELL_PATH_SQ)|' \
             -e 's|@@BUILD_DIR@@|$(shell pwd)|' \
 -           -e 's|@@PROG@@|$(@F)|' < $< > $@ && \
 +           -e 's|@@PROG@@|$(patsubst test-%,t/helper/test-%,$(@F))|' < $< > $@ && \
        chmod +x $@
  
  # GNU make supports exporting all variables by "export" without parameters.
@@@ -2239,25 -2231,25 +2245,25 @@@ perf: al
  
  .PHONY: test perf
  
 -test-ctype$X: ctype.o
 +t/helper/test-ctype$X: ctype.o
  
 -test-date$X: date.o ctype.o
 +t/helper/test-date$X: date.o ctype.o
  
 -test-delta$X: diff-delta.o patch-delta.o
 +t/helper/test-delta$X: diff-delta.o patch-delta.o
  
 -test-line-buffer$X: vcs-svn/lib.a
 +t/helper/test-line-buffer$X: vcs-svn/lib.a
  
 -test-parse-options$X: parse-options.o parse-options-cb.o
 +t/helper/test-parse-options$X: parse-options.o parse-options-cb.o
  
 -test-svn-fe$X: vcs-svn/lib.a
 +t/helper/test-svn-fe$X: vcs-svn/lib.a
  
  .PRECIOUS: $(TEST_OBJS)
  
 -test-%$X: test-%.o GIT-LDFLAGS $(GITLIBS)
 +t/helper/test-%$X: t/helper/test-%.o GIT-LDFLAGS $(GITLIBS)
        $(QUIET_LINK)$(CC) $(ALL_CFLAGS) -o $@ $(ALL_LDFLAGS) $(filter %.o,$^) $(filter %.a,$^) $(LIBS)
  
 -check-sha1:: test-sha1$X
 -      ./test-sha1.sh
 +check-sha1:: t/helper/test-sha1$X
 +      t/helper/test-sha1.sh
  
  SP_OBJ = $(patsubst %.o,%.sp,$(C_OBJ))
  
@@@ -2404,25 -2396,31 +2410,25 @@@ quick-install-html
  
  ### Maintainer's dist rules
  
 -git.spec: git.spec.in GIT-VERSION-FILE
 -      sed -e 's/@@VERSION@@/$(GIT_VERSION)/g' < $< > $@+
 -      mv $@+ $@
 -
  GIT_TARNAME = git-$(GIT_VERSION)
 -dist: git.spec git-archive$(X) configure
 +dist: git-archive$(X) configure
        ./git-archive --format=tar \
                --prefix=$(GIT_TARNAME)/ HEAD^{tree} > $(GIT_TARNAME).tar
        @mkdir -p $(GIT_TARNAME)
 -      @cp git.spec configure $(GIT_TARNAME)
 +      @cp configure $(GIT_TARNAME)
        @echo $(GIT_VERSION) > $(GIT_TARNAME)/version
        @$(MAKE) -C git-gui TARDIR=../$(GIT_TARNAME)/git-gui dist-version
        $(TAR) rf $(GIT_TARNAME).tar \
 -              $(GIT_TARNAME)/git.spec \
                $(GIT_TARNAME)/configure \
                $(GIT_TARNAME)/version \
                $(GIT_TARNAME)/git-gui/version
        @$(RM) -r $(GIT_TARNAME)
        gzip -f -9 $(GIT_TARNAME).tar
  
 -rpm: dist
 -      $(RPMBUILD) \
 -              --define "_source_filedigest_algorithm md5" \
 -              --define "_binary_filedigest_algorithm md5" \
 -              -ta $(GIT_TARNAME).tar.gz
 +rpm::
 +      @echo >&2 "Use distro packaged sources to run rpmbuild"
 +      @false
 +.PHONY: rpm
  
  htmldocs = git-htmldocs-$(GIT_VERSION)
  manpages = git-manpages-$(GIT_VERSION)
@@@ -2458,8 -2456,8 +2464,8 @@@ profile-clean
        $(RM) $(addsuffix *.gcno,$(addprefix $(PROFILE_DIR)/, $(object_dirs)))
  
  clean: profile-clean coverage-clean
 -      $(RM) *.o *.res refs/*.o block-sha1/*.o ppc/*.o compat/*.o compat/*/*.o
 -      $(RM) xdiff/*.o vcs-svn/*.o ewah/*.o builtin/*.o
 +      $(RM) *.res
 +      $(RM) $(OBJECTS)
        $(RM) $(LIB_FILE) $(XDIFF_LIB) $(VCSSVN_LIB)
        $(RM) $(ALL_PROGRAMS) $(SCRIPT_LIB) $(BUILT_INS) git$X
        $(RM) $(TEST_PROGRAMS) $(NO_INSTALL)
@@@ -2498,7 -2496,6 +2504,7 @@@ ALL_COMMANDS += git-gui git-citoo
  
  .PHONY: check-docs
  check-docs::
 +      $(MAKE) -C Documentation lint-docs
        @(for v in $(ALL_COMMANDS); \
        do \
                case "$$v" in \