Make version.h depend on git changes

Originally committed as revision 22421 to svn://svn.ffmpeg.org/ffmpeg/trunk

Makefile

@@ -86,9 +86,10 @@ tools/%.o: tools/%.c
 ffplay.o ffplay.d: CFLAGS += $(SDL_CFLAGS)
 
 VERSION_SH  = $(SRC_PATH_BARE)/version.sh
+GIT_LOG     = $(SRC_PATH_BARE)/.git/logs/HEAD
 SVN_ENTRIES = $(SRC_PATH_BARE)/.svn/entries
 
-.version: $(wildcard $(SVN_ENTRIES)) $(VERSION_SH) config.mak
+.version: $(wildcard $(GIT_LOG) $(SVN_ENTRIES)) $(VERSION_SH) config.mak
 .version: M=@
 
 version.h .version: