Add a check to ap_die() to make sure the filter stack is sane and

contains the correct basic filters when an error occurs. This fixes
a problem where headers are not being sent on error.
PR:
Obtained from:
Submitted by:	John Sterling
Reviewed by:


git-svn-id: https://svn.apache.org/repos/asf/httpd/httpd/trunk@89253 13f79535-47bb-0310-9956-ffa450edef68