generic: Check clearing of SGID in chmod and acl_set_file

generic: Check clearing of SGID in chmod and acl_set_file

Check if SGID is cleared upon chmod / setfacl when the owner is not
in the owning group.  As of today, the kernel fails to clear SGID in
setxattr (which is what acl_set_file is implemented on top of) in
that case; see this patch:

  https://patchwork.kernel.org/patch/9290507/

Signed-off-by: Andreas Gruenbacher <agruenba@redhat.com>
Cc: Jan Kara <jack@suse.cz>
Reviewed-by: Eryu Guan <eguan@redhat.com>
Signed-off-by: Eryu Guan <eguan@redhat.com>