- Add reallyall option to configure to build everything that can be built with

  the available libs.
- Remove redundant --with-distcache option. Simply enable distcache if
  mod_socache_dc is selected.
- Enable serf support by default if serf is available in /usr.


git-svn-id: https://svn.apache.org/repos/asf/httpd/httpd/trunk@956221 13f79535-47bb-0310-9956-ffa450edef68