Abort apache buildconf if apr buildconf or apr-util buildconf fails.

Otherwise, the error message from apr or apr-util (e.g., invalid libtool
version) is lost in the stream of output.


git-svn-id: https://svn.apache.org/repos/asf/httpd/httpd/trunk@88602 13f79535-47bb-0310-9956-ffa450edef68