Merge r1364695 from trunk:

mod_lbmethod_heartbeat, mod_heartmonitor: Respect DefaultRuntimeDir/
DEFAULT_REL_RUNTIMEDIR for the heartbeat storage file.

Submitted by: trawick
Reviewed/backported by: jim


git-svn-id: https://svn.apache.org/repos/asf/httpd/httpd/branches/2.4.x@1455218 13f79535-47bb-0310-9956-ffa450edef68