add back the DefaultRuntimeDir/DEFAULT_REL_RUNTIMEDIR stuff

that is not in 2.4.x

The trunk patches for these all have some configuration breakage
as 2.4.x interprets the individual directive or API parameter as
relative to ServerRoot whereas trunk interprets everything
relative to DefaultRuntimeDir.


git-svn-id: https://svn.apache.org/repos/asf/httpd/httpd/trunk@1373121 13f79535-47bb-0310-9956-ffa450edef68