Fixed buildconf hint about missing APR/APU.

With the httpd 2.2.x branch we use by default the APR 1.4.x
and APU 1.3.x branch and not trunk; also most likely the 2.2.x
configure stuff is not prepared for APR-2 where APR and APU are
now merged and no longer in separate directories.


git-svn-id: https://svn.apache.org/repos/asf/httpd/httpd/branches/2.2.x@1068857 13f79535-47bb-0310-9956-ffa450edef68