Minor clean-up

git-svn-id: https://svn.apache.org/repos/asf/tomcat/trunk@1580591 13f79535-47bb-0310-9956-ffa450edef68
Fix https://issues.apache.org/bugzilla/show_bug.cgi?id=56293
Cache resources loaded by the class loader from /META-INF/services/ for better performance for repeated look ups.

git-svn-id: https://svn.apache.org/repos/asf/tomcat/trunk@1580598 13f79535-47bb-0310-9956-ffa450edef68