Merge branch 'ma/doc-diff-doc-vs-doctor-comparison'

Dev support update to make it easier to compare two formatted
results from our documentation.

* ma/doc-diff-doc-vs-doctor-comparison:
doc-diff: add `--cut-header-footer`
doc-diff: support diffing from/to AsciiDoc(tor)
doc-diff: let `render_tree()` take an explicit directory name
Doc: auto-detect changed build flags

diff --cc Documentation/Makefile
index ccac771d3fb5ecb863c64a782a947a76593df397,b534623012daacfd651916b454d2598c9508d9e9..4e4dd7ecf14919fa3d5735daa6b87c8addcff1e8
--- 1/Documentation/Makefile
--- 2/Documentation/Makefile
+++ b/Documentation/Makefile
@@@ -340,13 -349,14 +349,14 @@@ clean
        $(RM) SubmittingPatches.txt
        $(RM) $(cmds_txt) $(mergetools_txt) *.made
        $(RM) manpage-base-url.xsl
+       $(RM) GIT-ASCIIDOCFLAGS
  
- $(MAN_HTML): %.html : %.txt asciidoc.conf asciidoctor-extensions.rb
 -$(MAN_HTML): %.html : %.txt asciidoc.conf GIT-ASCIIDOCFLAGS
++$(MAN_HTML): %.html : %.txt asciidoc.conf asciidoctor-extensions.rb GIT-ASCIIDOCFLAGS
        $(QUIET_ASCIIDOC)$(RM) $@+ $@ && \
        $(TXT_TO_HTML) -d manpage -o $@+ $< && \
        mv $@+ $@
  
- $(OBSOLETE_HTML): %.html : %.txto asciidoc.conf asciidoctor-extensions.rb
 -$(OBSOLETE_HTML): %.html : %.txto asciidoc.conf GIT-ASCIIDOCFLAGS
++$(OBSOLETE_HTML): %.html : %.txto asciidoc.conf asciidoctor-extensions.rb GIT-ASCIIDOCFLAGS
        $(QUIET_ASCIIDOC)$(RM) $@+ $@ && \
        $(TXT_TO_HTML) -o $@+ $< && \
        mv $@+ $@
@@@ -358,12 -368,12 +368,12 @@@ manpage-base-url.xsl: manpage-base-url.
        $(QUIET_XMLTO)$(RM) $@ && \
        $(XMLTO) -m $(MANPAGE_XSL) $(XMLTO_EXTRA) man $<
  
- %.xml : %.txt asciidoc.conf asciidoctor-extensions.rb
 -%.xml : %.txt asciidoc.conf GIT-ASCIIDOCFLAGS
++%.xml : %.txt asciidoc.conf asciidoctor-extensions.rb GIT-ASCIIDOCFLAGS
        $(QUIET_ASCIIDOC)$(RM) $@+ $@ && \
        $(TXT_TO_XML) -d manpage -o $@+ $< && \
        mv $@+ $@
  
- user-manual.xml: user-manual.txt user-manual.conf asciidoctor-extensions.rb
 -user-manual.xml: user-manual.txt user-manual.conf GIT-ASCIIDOCFLAGS
++user-manual.xml: user-manual.txt user-manual.conf asciidoctor-extensions.rb GIT-ASCIIDOCFLAGS
        $(QUIET_ASCIIDOC)$(RM) $@+ $@ && \
        $(TXT_TO_XML) -d book -o $@+ $< && \
        mv $@+ $@