mpm_winnt: Following up on r1801655, add a comment that explains the

reason to choose the LIFO processing order for completion contexts.

It would be better to keep this important information in the code, instead
of just having it in the log message.


git-svn-id: https://svn.apache.org/repos/asf/httpd/httpd/trunk@1801710 13f79535-47bb-0310-9956-ffa450edef68