[libc][pthread] pthread_rwlock_t is linux specific

[nickdesaulniers]

41fecca added support for pthread_rwlock_t. Our user facing header (libc/include/llvm-libc-types/pthread_rwlock_t.h) defines this type in terms of __futex_word, which is perhaps linux specific (perhaps libc/include/llvm-libc-types/__futex_word.h should #error when __linux__ is not defined? cc @SchrodingerZhu

I suspect this will be a problem for supporting this type on non-linux. Changing the type will probably need to update PTHREAD_RWLOCK_INITIALIZER in libc/include/llvm-libc-macros/pthread-macros.h.

#126314

[llvmbot]

@llvm/issue-subscribers-libc

Author: Nick Desaulniers (nickdesaulniers)

41fecca added support for pthread_rwlock_t. Our user facing header (libc/include/llvm-libc-types/pthread_rwlock_t.h) defines this type in terms of `__futex_word`, which is perhaps linux specific (perhaps libc/include/llvm-libc-types/__futex_word.h should `#error` when `__linux__` is not defined? cc @SchrodingerZhu

I suspect this will be a problem for supporting this type on non-linux. Changing the type will probably need to update PTHREAD_RWLOCK_INITIALIZER in libc/include/llvm-libc-macros/pthread-macros.h.

#126314