Assorted fixes for the OS/2 mpm:

Assorted fixes for the OS/2 mpm:
- pchild really should be thread local
- clean_child_exit() should call _endthread(), not exit()
- Use DosSleep() for delay in wait_or_timeout() instead of ap_select
- Rework logic of searching for listen rec in child main, was getting hung
  in infinite loop when two sockets were being listened to. NOTE: I got it
  from prefork.c originally so that's probably broken too.
- Remove a debugging fprintf I accidentally left in...

git-svn-id: https://svn.apache.org/repos/asf/httpd/httpd/trunk@83453 13f79535-47bb-0310-9956-ffa450edef68