stop defining ap_scoreboard_fname multiple times in Mpmt_pthread MPM.

Submitted by:	Victor J. Orlikowski <vjo@raleigh.ibm.com>
Reviewed by:	Ryan Bloom


git-svn-id: https://svn.apache.org/repos/asf/httpd/httpd/trunk@85651 13f79535-47bb-0310-9956-ffa450edef68