linux: Use INTERNAL_SYSCALL on fstatat{64}

linux: Use INTERNAL_SYSCALL on fstatat{64}

Although not required by the standards, some code expects that a
successful stat call should not set errno.  However since aa03f722f3b99
'linux: Add {f}stat{at} y2038 support', on 32-bit systems with 32-bit
time_t supporrt, stat implementation will first issues __NR_statx and
if it fails with ENOSYS issue the system stat syscall.

On architecture running on kernel without __NR_statx support the
first call will set the errno to ENOSYS, even when the following stat
syscall might not fail.

This patch fixes by using INTERNAL_SYSCALL and only setting the errno
value when function returns.

Checked on i686-linux-gnu, x86_64-linux-gnu, sparc64-linux-gnu,
sparcv9-linux-gnu, powerpc64-linux-gnu, powerpc64le-linux-gnu,
arm-linux-gnueabihf, and aarch64-linux-gnu.