Avoid redundant strlen() calls by using apr_brigade_write() instead of

Avoid redundant strlen() calls by using apr_brigade_write() instead of
apr_brigade_puts().  There is still some redundancy--it'd be ideal if there
were an apr_pstrcat() variant that returned the length of the string since
it computes it (twice) anyway so we didn't have to do it yet again.  Until
such a beast exists, computing the length three times is better than four.
:-/

git-svn-id: https://svn.apache.org/repos/asf/httpd/httpd/trunk@89516 13f79535-47bb-0310-9956-ffa450edef68