prefork MPM: Run cleanups for final request when process exits gracefully,

in spite of faulty apr_reslist code.

Backports: r943650
PR: 43857
Submitted by: Tom Donovan
Reviewed by: trawick, rjung, wrowe
 

git-svn-id: https://svn.apache.org/repos/asf/httpd/httpd/branches/2.2.x@1021621 13f79535-47bb-0310-9956-ffa450edef68