Align flush() implementations

git-svn-id: https://svn.apache.org/repos/asf/tomcat/trunk@1478085 13f79535-47bb-0310-9956-ffa450edef68
Pull-up flush()

git-svn-id: https://svn.apache.org/repos/asf/tomcat/trunk@1478087 13f79535-47bb-0310-9956-ffa450edef68
Align endRequest() implementations and pull-up changes in over-riding methods

git-svn-id: https://svn.apache.org/repos/asf/tomcat/trunk@1478089 13f79535-47bb-0310-9956-ffa450edef68