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