Commit a few changes to the mpmt_pthread and dexter MPMs. These basically

fix the error checking for one return from ap_poll, and use ap_pcalloc to
allocate the listenfds array.  By using listenfds, we can avoid making
an unnecessary call to ap_create_tcp_socket.
Submitted by:	Jeff Trawick
Reviewed by:	Ryan Bloom


git-svn-id: https://svn.apache.org/repos/asf/httpd/httpd/trunk@85661 13f79535-47bb-0310-9956-ffa450edef68