Prototypes for the visible functions in mpm_common.c.

Submitted by:	Jeff Trawick <trawickj@bellsouth.net>
Reviewed by:	Roy Fielding


git-svn-id: https://svn.apache.org/repos/asf/httpd/httpd/trunk@85256 13f79535-47bb-0310-9956-ffa450edef68