valgrind: disable mpicc and make Linux only

[danielnachun]

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This disables mpicc support in valgrind, which seems to cause build failures on host systems with mpich or OpenMPI installed. If we ever get a request to add support for mpicc to valgrind, we'd probably have to add mpich or open-mpi as a dependency. Additionally the configure argument --build=amd64-darwin should only be used on macOS.

Moved to homebrew-core from https://github.com/Homebrew/linuxbrew-core/pull/21870.

[SMillerDev]

This formula should probably just be linux only because it doesn't run on any of our supported macOS versions

[carlocab]

depends_on maximum_macos: :sierra would work too, though I can see the advantages of it being Linux-only.

There also seems to be a version of valgrind that works at least until Catalina: https://github.com/LouisBrunner/valgrind-macos

[danielnachun]

Since there is a tap that provides a working version of valgrind for all versions of macOS, I'm inclined to make this Linux only. Hopefully the patches in that fork of valgrind can be integrated into the official release so that it will once again work in macOS, but that is an issue for upstream to deal with.

[danielnachun]

Actually if we make this Linux only, should I close this pull request? Does homebrew-core allow Linux only formulae?

[SeekingMeaning]

Does homebrew-core allow Linux only formulae?

Yep, for example: #65300

This is how I would convert it to Linux-only: https://gist.github.com/SeekingMeaning/10db0c2f3a8a29fa760b6903ad808671/revisions

We might even be able to delete the skip_clean stanza, but I'm not completely certain (Homebrew/legacy-homebrew#2150 might shed some light)

[danielnachun]

Thanks for the revisions, I'll try removing skip_clean on my Linux install and see if it breaks anything. Everything else looks pretty straightforward.

[SeekingMeaning]

Also add Formula/valgrind.rb to .github/workflows/tests-linux.yml

[iMichka]

I agree that this can be made linux-only. Though we also try to disable valgrind support when possible in all other formulae.