ap_new_connection() returns NULL if an error occurred (prefork MPM

and ap_new_connection() were changed last week)

I have skipped putting the change into WinNT MPM and mod_proxy.  I
left a note in the mod_proxy code; for the NT MPM I think I can talk
somebody into doing the right thing for me.


git-svn-id: https://svn.apache.org/repos/asf/httpd/httpd/trunk@87982 13f79535-47bb-0310-9956-ffa450edef68