merge this fix from 2.1-dev:

   mod_log_config: Fix corruption of buffered logs with threaded
   MPMs.  PR 25520.

PR:            25520
Reviewed by:   stoddard, jerenkrantz


git-svn-id: https://svn.apache.org/repos/asf/httpd/httpd/branches/APACHE_2_0_BRANCH@102845 13f79535-47bb-0310-9956-ffa450edef68