Add fatal exception hook for use by debug modules. The hook is only

available if the --enable-exception-hook configure parm is used.

Sample users at http://httpd.apache.org/~trawick/exception_hook.html


git-svn-id: https://svn.apache.org/repos/asf/httpd/httpd/trunk@101899 13f79535-47bb-0310-9956-ffa450edef68