Now that the kernel access control for quotactl(2) appears to work

Now that the kernel access control for quotactl(2) appears to work
properly, clean up quota(1).  quota(1) has the ability to query
quotas either directly from the kernel, or if that fails, by reading
the quota.user or quota.group files specified for the file system
in /etc/fstab.  The setuid bit existed solely (apparently) to let
non-operator users query their quotas and consumption when quotas
weren't enabled for the file system.

o Remove the setuid bit from quota(1).

o Remove the logic used by quota(1) when running setuid to prevent
  users from querying the quotas of other users or groups.  Note
  that this papered over previously broken kernel access control.