Fix https://issues.apache.org/bugzilla/show_bug.cgi?id=56139
Avoid a web application class loader leak in some unit tests when running on Windows.

git-svn-id: https://svn.apache.org/repos/asf/tomcat/tc7.0.x/trunk@1568937 13f79535-47bb-0310-9956-ffa450edef68