Add httpd -t (test) option for running configuration syntax tests only. If

something is broken it complains and exits with a return code non-equal to 0.

This can be used manually by the user to check the Apache configuration after
editing and is also automatically used by apachectl on (graceful) restart
command to make sure Apache doesn't die on restarts because of a configuration
which is now broken since the last (re)start.

This way `apachectl restart' can be used inside cronjobs without having to
expect Apache to be falling down. Additionally the httpd -t can be run via
`apachectl configtest'.

Submitted by: Ralf S. Engelschall
Reviewed by: Martin Kraemer, Brian Behlendorf, Jim Jagielski, Dean Gaudet
PR: 2393


git-svn-id: https://svn.apache.org/repos/asf/httpd/httpd/branches/1.3.x@81531 13f79535-47bb-0310-9956-ffa450edef68