Fix the Perchild MPM. This does work now. This change has us using

Fix the Perchild MPM.  This does work now.  This change has us using
socketpair instead of sockets created with AF_UNIX.  There is very little
chance this will work anywhere other than Linux, but it is a start.  I
have a machine with two virtual hosts, which are started as two different
users.  When I make requests for each virtual host, they pass the request
to the correct child process.  It is possible for a virtual host to have
multiple child processes all with the same user ID, and they all share
the responsability for answering requests.

There are a lot of bugs in this code, and it is not for the faint
hearted, but it works, and that's saying quite a bit in my mind.

Docs coming tomorrow.  Right now, it's time to sleep.

git-svn-id: https://svn.apache.org/repos/asf/httpd/httpd/trunk@85983 13f79535-47bb-0310-9956-ffa450edef68