Small improvement to the test

git-svn-id: https://svn.apache.org/repos/asf/tomcat/tc7.0.x/trunk@1646464 13f79535-47bb-0310-9956-ffa450edef68
Simplify. NioChannel.getAttachment(boolean) was only ever called with a parameter of false.

git-svn-id: https://svn.apache.org/repos/asf/tomcat/tc7.0.x/trunk@1646465 13f79535-47bb-0310-9956-ffa450edef68
Use the provided atomic method to replace the attachment and return a reference to the old value.

git-svn-id: https://svn.apache.org/repos/asf/tomcat/tc7.0.x/trunk@1646466 13f79535-47bb-0310-9956-ffa450edef68
Fix https://issues.apache.org/bugzilla/show_bug.cgi?id=57340
Ensure that Socket and SocketWrapper are only returned to the cache once on socket close (it is possible for multiple threads to call close concurrently).

git-svn-id: https://svn.apache.org/repos/asf/tomcat/tc7.0.x/trunk@1646468 13f79535-47bb-0310-9956-ffa450edef68