[libc] Remove faccessat entrypoint if faccessat2 syscall is not available (#164936)

[#163091](https://github.com/llvm/llvm-project/issues/163091)

Remove unistd.faccessat entrypoint for x86 linux if faccessat2 syscall
is not available. Tested with non existent symbol and exclusion works.

GitOrigin-RevId: b1acd6df03d3e0dfaee00191a807142a65b2e212
2 files changed