Simplify some overly complicated code using apr_brigade_putstrs and apr_pstrcat

Submitted by: Christophe Jaillet <christophe jaillet wanadoo fr>,
              Stefan Fritsch


git-svn-id: https://svn.apache.org/repos/asf/httpd/httpd/trunk@1159896 13f79535-47bb-0310-9956-ffa450edef68