Require threaded Perl when compilling with httpd >= 2.4.0. Remove unused option
MP_NONTHREADED_OK and replace it with MP_NO_THREADS.

This is follow up of r1151822.


git-svn-id: https://svn.apache.org/repos/asf/perl/modperl/branches/httpd24threading@1590627 13f79535-47bb-0310-9956-ffa450edef68