patchWindows: force-recompile git.res for differing architectures

> From: Johannes Schindelin <johannes.schindelin@gmx.de>
> 
> 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>
> ---
>   Makefile | 2 +-
>   1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/Makefile b/Makefile
> index bbfbb4292d..8375736c32 100644
> --- a/Makefile
> +++ b/Makefile
> @@ -2110,7 +2110,7 @@ $(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= -DMICRO= -DPATCHLEVEL=, $(wordlist 1, 4, \
>   	    $(shell echo $(GIT_VERSION) 0 0 0 0 | tr '.a-zA-Z-' ' '))) \
> 

> Am 06.11.18 um 15:55 schrieb Johannes Schindelin via GitGitGadget:
>> From: Johannes Schindelin <johannes.schindelin@gmx.de>
>>
>> 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).
>
> On Linux, when I recompile for a different architecture, CFLAGS would
> change, so I would have thought that GIT-CFLAGS were the natural
> choice for a dependency. Don't they change in this case on Windows,
> too?

> Johannes Sixt <j6t@kdbg.org> writes:
>> On Linux, when I recompile for a different architecture, CFLAGS would
>> change, so I would have thought that GIT-CFLAGS were the natural
>> choice for a dependency. Don't they change in this case on Windows,
>> too?
> 
> Depending on GIT-CFLAGS would have a better chance of being safe, I
> guess, even though it can at times be overly safe, than GIT-PREFIX,
> I suspect.  As a single user target in Makefile, which is only used
> by Dscho, who intends to stick to /mingw(32|64)/ convention til the
> end of time, I think the posted patch is OK, though.

> Am 07.11.18 um 02:32 schrieb Junio C Hamano:
>> Johannes Sixt <j6t@kdbg.org> writes:
>>> On Linux, when I recompile for a different architecture, CFLAGS would
>>> change, so I would have thought that GIT-CFLAGS were the natural
>>> choice for a dependency. Don't they change in this case on Windows,
>>> too?
>>
>> Depending on GIT-CFLAGS would have a better chance of being safe, I
>> guess, even though it can at times be overly safe, than GIT-PREFIX,
>> I suspect.  As a single user target in Makefile, which is only used
>> by Dscho, who intends to stick to /mingw(32|64)/ convention til the
>> end of time, I think the posted patch is OK, though.
>
> I think that it's not only Dscho who uses the target (my build
> environment, for example, is different from Dscho's and compiles
> git.res, too). But since the patch helps him most and doesn't hurt
> others, it is good to go. No objection from my side.

> Johannes Sixt <j6t@kdbg.org> writes:
> 
> > Am 07.11.18 um 02:32 schrieb Junio C Hamano:
> >> Johannes Sixt <j6t@kdbg.org> writes:
> >>> On Linux, when I recompile for a different architecture, CFLAGS would
> >>> change, so I would have thought that GIT-CFLAGS were the natural
> >>> choice for a dependency. Don't they change in this case on Windows,
> >>> too?
> >>
> >> Depending on GIT-CFLAGS would have a better chance of being safe, I
> >> guess, even though it can at times be overly safe, than GIT-PREFIX,
> >> I suspect.  As a single user target in Makefile, which is only used
> >> by Dscho, who intends to stick to /mingw(32|64)/ convention til the
> >> end of time, I think the posted patch is OK, though.
> >
> > I think that it's not only Dscho who uses the target (my build
> > environment, for example, is different from Dscho's and compiles
> > git.res, too). But since the patch helps him most and doesn't hurt
> > others, it is good to go. No objection from my side.
> 
> Yeah, that was phrased poorly.  What I meant was by "only by Dscho"
> was "only by those who share the convention that GIT-PREFIX is
> changed if and only if targetting a different arch".
> 
> Anyway, I just wanted to say that GIT-PREFIX may not be precise
> enough but would give sufficient signal; GIT-CFLAGS may be a more
> cautious choice, but it may change a bit too often ;-).