Windows: force-recompile git.res for differing architectures

When git.rc is compiled into git.res, the result is actually dependent
on the architecture. That is, you cannot simply link a 32-bit git.res
into a 64-bit git.exe.

Therefore, to allow 32-bit and 64-bit builds in the same directory, we
let git.res depend on GIT-PREFIX so that it gets recompiled when
compiling for a different architecture (this works because the exec path
changes based on the architecture: /mingw32/libexec/git-core for 32-bit
and /mingw64/libexec/git-core for 64-bit).

Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>

Author: dscho

Makefile

@@ -1760,7 +1760,7 @@ $(SCRIPT_LIB) : % : %.sh GIT-SCRIPT-DEFINES
 	$(QUIET_GEN)$(cmd_munge_script) && \
 	mv $@+ $@
 
-git.res: git.rc GIT-VERSION-FILE
+git.res: git.rc GIT-VERSION-FILE GIT-PREFIX
 	$(QUIET_RC)$(RC) \
 	  $(join -DMAJOR= -DMINOR=, $(wordlist 1,2,$(subst -, ,$(subst ., ,$(GIT_VERSION))))) \
 	  -DGIT_VERSION="\\\"$(GIT_VERSION)\\\"" $< -o $@