Fix https://issues.apache.org/bugzilla/show_bug.cgi?id=55772
Ensure that the request and response are recycled after an error during async processing.

git-svn-id: https://svn.apache.org/repos/asf/tomcat/tc7.0.x/trunk@1542269 13f79535-47bb-0310-9956-ffa450edef68