perform_groupdel() tries to delete a group irrespective if other
users have it as their primary group, thus the call to groupdel will
fail with the following error error:
groupdel: cannot remove the primary group of user '<user>'
Add a check to perform_groupdel() to determine if there are other
users and keep the group, printing a warning. This is called right
after a user is deleted to delete it's group. If the last user is
deleted, only then the group is also deleted.
Signed-off-by: Ioan-Adrian Ratiu <adrian.ratiu@ni.com> Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>
