Merge branch 'np/delta'

* np/delta:
builtin-pack-objects.c: avoid bogus gcc warnings
threaded delta search: proper locking for cache accounting
threaded delta search: add pack.threads config variable
fix threaded delta search locking
threaded delta search: specify number of threads at run time
threaded delta search: better chunck split point
threaded delta search: refine work allocation
basic threaded delta search
rearrange delta search progress reporting
localize window memory usage accounting
straighten the list of objects to deltify

diff --cc Documentation/git-pack-objects.txt
Simple merge

diff --cc Makefile
index 78cdaa155ba424475fe091cd19cf212e32fcfc2f,a92fb316950155cd0e3d27d61cbf16432b2e3386..40567ece1430e6d59c7f877f9f5861505d22d419
--- 1/Makefile
--- 2/Makefile
+++ b/Makefile
@@@ -670,11 -664,12 +673,16 @@@ ifdef NO_HSTRERRO
        COMPAT_CFLAGS += -DNO_HSTRERROR
        COMPAT_OBJS += compat/hstrerror.o
  endif
 +ifdef NO_MEMMEM
 +      COMPAT_CFLAGS += -DNO_MEMMEM
 +      COMPAT_OBJS += compat/memmem.o
 +endif
  
+ ifdef THREADED_DELTA_SEARCH
+       BASIC_CFLAGS += -DTHREADED_DELTA_SEARCH
+       EXTLIBS += -lpthread
+ endif
+ 
  ifeq ($(TCLTK_PATH),)
  NO_TCLTK=NoThanks
  endif