Win32: ap_max_requests_per_child should not be a local static in mpm_winnt.c.

This was preventing the MaxRequestsPerChild config directive from working
properly.

Handle MaxRequestsPerChild a bit more sanely.  When MaxRequestsPerChild is hit,
the child signals an event that causes the main child thread to signal the parent
to restart.


git-svn-id: https://svn.apache.org/repos/asf/httpd/httpd/trunk@91578 13f79535-47bb-0310-9956-ffa450edef68