Only lower case the canonical name on a call to ap_os_canonical_filename()

if ap_os_case_canonical_filename() fails to retieve the information from the
file system, at least we have the casing from the request.


git-svn-id: https://svn.apache.org/repos/asf/httpd/httpd/branches/1.3.x@93346 13f79535-47bb-0310-9956-ffa450edef68