[libc-commits] [libc] [libc] add proxy header for struct_sigaction (PR #96224)

[Nick Desaulniers via libc-commits]

https://github.com/nickdesaulniers commented:

Can we clean up test/src/signal/sigaltstack_test.cpp with this change?

and test/src/signal/sigaction_test.cpp
src/signal/linux/signal.cpp

https://github.com/llvm/llvm-project/pull/96224