[gmp] Fix builds for x64-linux

[rjindael]

Fixes #47536

• Changes comply with the maintainer guide.
• SHA512s are updated for each updated download.
• The "supports" clause reflects platforms that may be fixed by this new version.
• Any fixed CI baseline entries are removed from that file.
• Any patches that are no longer applied are deleted from the port's directory.
• The version database is fixed by rerunning ./vcpkg x-add-version --all and committing the result.
• Only one version is added to each modified port's versions file.

This pull request merges the following two commits from the GMP upstream repository:

• Complete function prototype in acinclude.m4 for C23 compatibility: https://gmplib.org/repo/gmp/rev/8e7bb4ae7a18
• Remove broken __builtin_alloca configure test: https://gmplib.org/repo/gmp/rev/1dc7d5dabc8d

These two revisions are necessary for producing a proper configure on x64-linux, but have yet to be part of a release tarball which vcpkg can download from. Therefore, this pull request includes a pre-install patch that applies them.

[rjindael]

@microsoft-github-policy-service agree

[JavierMatosD]

@rjindael, I'm not seeing this port fail for x64-linux in our CI. Can you give me the repro steps?

[rjindael]

@rjindael, I'm not seeing this port fail for x64-linux in our CI. Can you give me the repro steps?

Hi, full reproduction steps are available at this issue, with logs and compiler info: #47536. I am running Arch Linux with the latest Clang/LLVM.

Please note this was already patched in upstream GMP. Microsoft CI may not be using a compiler that uses C23, and therefore it will not fail with this conftest, seeing as it has a method that fails because that form of declaration became deprecated.