generic/314: don't test SGID behavior after setfacl

generic/314: don't test SGID behavior after setfacl

Linux 4.9 (since commit 073931017b49: "posix_acl: Clear SGID bit
when setting file permissions") now may clear the SGID bit when
setting a POSIX ACL, to match chmod() behavior.  This was making
generic/314 fail. Since SGID bit clearing on setfacl is already
tested by generic/375, just remove the problematic portion of
generic/314.

Signed-off-by: Eric Biggers <ebiggers@google.com>
Reviewed-by: Eryu Guan <eguan@redhat.com>
Signed-off-by: Eryu Guan <eguan@redhat.com>