Backport a patch similar to r580433, but similar to the apr-1.2

specific server/log.c r602467, take into account the fact that 
apr's flags could not be adjusted.

Backports: 2.2.x branch r607311

git-svn-id: https://svn.apache.org/repos/asf/httpd/httpd/branches/2.0.x@607312 13f79535-47bb-0310-9956-ffa450edef68