Retain persistence on a 204 (No Content) response.

Correct send_http_trace() to use r->the_request instead of constructing
the request-line from its parsed components.

Submitted by: Dean Gaudet
Reviewed by: Roy Fielding


git-svn-id: https://svn.apache.org/repos/asf/httpd/httpd/branches/1.3.x@77622 13f79535-47bb-0310-9956-ffa450edef68