[compiler-rt] [compiler-rt][Mips] Align definition of __sanitizer_sigaction with musl (PR #124494)

[Vitaly Buka via llvm-commits]

https://github.com/vitalybuka requested changes to this pull request.

Could you please do not reformat in the same PR, or split format and change into 2 different commits?

https://github.com/llvm/llvm-project/pull/124494