Share fdqueue code between MPMs event and worker.

This first step moves the content of server/mpm/event/fdqueue.c to
the existing server/mpm_unix.c file, and the server/mpm/event/fdqueue.h file
to trunk/server/mpm_unix.h (untouched for now, simple svn move).

Will follow up with the necessary changes to mpm_unix.* for common code.



git-svn-id: https://svn.apache.org/repos/asf/httpd/httpd/trunk@1821526 13f79535-47bb-0310-9956-ffa450edef68