xfstests: generic/314, test sgid inheritance on subdirs

Tests if subdirectories created on the filesystem will properly inherit sgid bit
when this is set on the parent directory, once the process has the properly
permissions to create a subdirectory, this, should inherit parent's sgid bit if
this is set and irix_sgid_inherit sysctl is disabled.

V2: add missing source of "attr" file for _require_acls

V3: use _ls_l to filter out the selinux "."
    renumber to 314 to make the merge easier

V4: fix 314.out to the correct output

Thanks to Sandeen who have written this patch

Signed-off-by: Eric Sandeen <sandeen@redhat.com>
Signed-off-by: Carlos Maiolino <cmaiolino@redhat.com>
Reviewed-by: Ben Myers <bpm@sgi.com>
Signed-off-by: Ben Myers <bpm@sgi.com>

tests/generic/314.out

@@ -0,0 +1,4 @@
+QA output created by 314
+total 4
+drwxr-sr-x subdir
+drwxrwsr-x+ subdir2