Patching GMP for build-many-glibcs.py

[Florian Weimer]

* Joseph Myers:

> build-many-glibcs.py fails to build host-libraries on systems using GCC 15 
> because of a configure test incompatible with C23.  There has been no GMP 
> release since this was fixed in January.  The natural fix probably 
> involves providing a patched GMP tarball with the changes
>
> changeset:   18477:8e7bb4ae7a18
> user:        Marc Glisse <marc.glisse@inria.fr>
> date:        Wed Jan 29 22:38:02 2025 +0100
> files:       ChangeLog acinclude.m4
> description:
> Complete function prototype in acinclude.m4 for C23 compatibility
>
> changeset:   18484:d66d66d82dbb
> tag:         tip
> user:        Marc Glisse <marc.glisse@inria.fr>
> date:        Tue Apr 01 15:25:46 2025 +0200
> files:       ChangeLog acinclude.m4
> description:
> Add parameter names to function prototype
>
> backported, so that build-many-glibcs can download such a tarball until 
> there is a new GMP release - where should we put such a tarball for use by 
> build-many-glibcs.py?

Doesn't configuring CFLAGS="-Wall -O2 -std=gnu17" work?

Thanks,
Florian