perfcounter: assert when you try and set an average.
perfcounter: assert when you try and set an average.

If you're trying to set an average, you're probably doing it wrong.

Signed-off-by: Greg Farnum <0bcb4295d38ee745130ea5f2bb88ef4eef474e61@dreamhost.com>

ajnelson/ceph,ajnelson/ceph,ajnelson/ceph,ajnelson/ceph,ajnelson/ceph,ajnelson/ceph