Win32: Avoid busy wait which consumes 100% of the CPU when all the worker

threads are busy.

Submitted by: Igor Nazarenko
Reviewed by: Bill Stoddard


git-svn-id: https://svn.apache.org/repos/asf/httpd/httpd/branches/APACHE_2_0_BRANCH@98995 13f79535-47bb-0310-9956-ffa450edef68