Interim (slow) fix for p->sub_pool critical sections in alloc.c.

Affects win32 only.

Submitted by:	Ben Hyde
Reviewed by:	Dean Gaudet, Jim Jagielski


git-svn-id: https://svn.apache.org/repos/asf/httpd/httpd/branches/1.3.x@79787 13f79535-47bb-0310-9956-ffa450edef68