*) make find_liveprop() hook take a dav_resource rather than "r"

*) repos.c: liveprop hooks shouldn't respond if the resource is not an FS
     resource.
*) std_liveprop.c: use empty-elem form if value=="". return NOTDEF for the
     properties that we aren't ready to insert yet


git-svn-id: https://svn.apache.org/repos/asf/httpd/httpd/trunk@87087 13f79535-47bb-0310-9956-ffa450edef68