use sub_req_lookup_file for fsize and flastmod.

PR:		2355
Submitted by:	Manoj Kasichainula <manojk@raleigh.ibm.com>
Reviewed by:	Brian, Dean


git-svn-id: https://svn.apache.org/repos/asf/httpd/httpd/branches/1.3.x@81788 13f79535-47bb-0310-9956-ffa450edef68