Fix https://issues.apache.org/bugzilla/show_bug.cgi?id=57144
Improve ClientAbortException to provide non-null message in getMessage() and full class name in toString().

git-svn-id: https://svn.apache.org/repos/asf/tomcat/tc7.0.x/trunk@1634311 13f79535-47bb-0310-9956-ffa450edef68
Simplify code that waits for threads to finish. This allows to shorten wait time if threads finish earlier.

Merged r1634312 from tomcat/trunk.

git-svn-id: https://svn.apache.org/repos/asf/tomcat/tc7.0.x/trunk@1634313 13f79535-47bb-0310-9956-ffa450edef68