Avoid some memory allocations by using apr_table_setn where the string arguments

are allocated from the request pool and not modified later on.

Submitted by: Christophe JAILLET <christophe jaillet wanadoo fr>
PR: 51358


git-svn-id: https://svn.apache.org/repos/asf/httpd/httpd/trunk@1135084 13f79535-47bb-0310-9956-ffa450edef68