configure: move away from obsolete AC_OUTPUT args

AC_OUTPUT's use with arguments was obsoleted back at or before autoconf
2.50. Replace it with the preferred AC_CONFIG_FILES/AC_CONFIG_COMMANDS
calls.

git-svn-id: https://svn.apache.org/repos/asf/httpd/httpd/trunk@1753315 13f79535-47bb-0310-9956-ffa450edef68