Fix timeout logging in ap_process_request().

We can't use 'r' after ap_process_request_after_handler(), the core output
filter might have cleaned up its deferred bucket brigade on error, including
the EOR bucket.

Reported by: steffenal
Fixes SpiderLabs/ModSecurity#1542



git-svn-id: https://svn.apache.org/repos/asf/httpd/httpd/branches/2.4.x@1826543 13f79535-47bb-0310-9956-ffa450edef68