linux: Fix fchmodat with AT_SYMLINK_NOFOLLOW for 64 bit time_t (BZ#29097)

The AT_SYMLINK_NOFOLLOW emulation ues the default 32 bit stat internal
calls, which fails with EOVERFLOW if the file constains timestamps
beyond 2038.

Checked on i686-linux-gnu.

(cherry picked from commit 118a2aee)