Axe unnecessary trailing comma from server-status user output.

Backport of r1369904 from trunk.

Submitted by: trawick
Reviewed by: rjung, humbedooh
Backported by: rjung


git-svn-id: https://svn.apache.org/repos/asf/httpd/httpd/branches/2.4.x@1372369 13f79535-47bb-0310-9956-ffa450edef68