Save the test suite from crashing httpd.exe on start-up:
- Use the correct pool in MP_dINTERP_POOLa.
- Delay the use of MP_dINTERP_POOLa until it's really needed. We don't seem to have an interpreter available at this time, but it so happens that the test suite doesn't exercise going this far through perl_parse_require_line() anyway, so this bypasses the crash for now.
- Add an early return with trace diagnostic when MP_dINTERP_POOLa returns NULL to continue bypassing the crash if the test suite is enhanced to exercise more of perl_parse_require_line(). The trace diagnostic will help alert us to the fact that the order of creating an interpreter vs. handling Require parsing is still unresolved.

Many thanks to Jeff Trawick++ for invaluable assistance in getting this far.

git-svn-id: https://svn.apache.org/repos/asf/perl/modperl/branches/httpd24threading@1539414 13f79535-47bb-0310-9956-ffa450edef68