Unix MPMs: Catch SIGFPE so that exception hooks and CoreDumpDirectory

can work after that terminating signal.

Submitted by: Eric Covener <covener gmail.com>
Reviewed by:  trawick



git-svn-id: https://svn.apache.org/repos/asf/httpd/httpd/trunk@500881 13f79535-47bb-0310-9956-ffa450edef68