Fix https://issues.apache.org/bugzilla/show_bug.cgi?id=56365
Reviewing and fixing StandardJarScanFilter implementation:
1. Do not parse the same system property 3 times. Once per class is enough.
2. In check() method do not do defensive copying of HashMap for each jar name that we are filtering.
It is unlikely that check() and setXxx() methods were called concurrently. If they were, then one can wait for the other to complete.

git-svn-id: https://svn.apache.org/repos/asf/tomcat/trunk@1590311 13f79535-47bb-0310-9956-ffa450edef68
Fix https://issues.apache.org/bugzilla/show_bug.cgi?id=56365
Correct errors in StandardJarScanFilter documentation.

git-svn-id: https://svn.apache.org/repos/asf/tomcat/trunk@1590313 13f79535-47bb-0310-9956-ffa450edef68