[libc] Fix types provided by fcntl.h header. (#219121)

According to POSIX, `<fcntl.h>` header should provide definitions for
`f_owner_ex` structure, `flock` structure, as well as `mode_t`, `off_t`,
and `pid_t` types. Reflect that in the YAML definition to ensure
generated `<fcntl.h>` indeed provide them. The type definitions
themselves were already present in the LLVM-libc.

This fixes another problem while building Clang on Linux against
LLVM-libc (issue #97191)

GitOrigin-RevId: fc2bd841deb2ac8ce5dfa0d0b9833f76deab65f9