Merge branch 'rj/make-clean'

Build optimization.

* rj/make-clean:
  Makefile: don't use a versioned temp distribution directory
  Makefile: don't try to clean old debian build product
  gitweb/Makefile: conditionally include ../GIT-VERSION-FILE
  Documentation/Makefile: conditionally include ../GIT-VERSION-FILE
  Documentation/Makefile: conditionally include doc.dep

diff --cc Documentation/Makefile
Simple merge

diff --cc Makefile
Simple merge