Merge r1496709,r1601995 from trunk:

core: factor out DEFAULT_HANDLER_NAME

Submitted by: jailletc36
Reviewed by: ylavic, trawick


git-svn-id: https://svn.apache.org/repos/asf/httpd/httpd/branches/2.4.x@1610017 13f79535-47bb-0310-9956-ffa450edef68