userns: Allow setting gid_maps without privilege when setgroups is disabled
userns: Allow setting gid_maps without privilege when setgroups is disabled

Now that setgroups can be disabled and not reenabled, setting gid_map
without privielge can now be enabled when setgroups is disabled.

This restores most of the functionality that was lost when unprivileged
setting of gid_map was removed.  Applications that use this functionality
will need to check to see if they use setgroups or init_groups, and if they
don't they can be fixed by simply disabling setgroups before writing to
gid_map.

Cc: 4fbacc2fa0ffdbb11bf1ad6925b886ebd08dd15f@vger.kernel.org
Reviewed-by: Andy Lutomirski <2cc0d0d76de2e6f37b92deeb83c85cb306fc5dc1@amacapital.net>
Signed-off-by: "Eric W. Biederman" <8a741aa8cbd77ebc4a56ddb528ce9fd15d42f034@xmission.com>

KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs