Ensure available() is consistent with isFinished()

git-svn-id: https://svn.apache.org/repos/asf/tomcat/trunk@1519478 13f79535-47bb-0310-9956-ffa450edef68
Simple non-blocking write example. Primarily written to have something to test AJP with. Sequential were chosen as it makes it easy to spot output corruption.

git-svn-id: https://svn.apache.org/repos/asf/tomcat/trunk@1519481 13f79535-47bb-0310-9956-ffa450edef68