Fix https://issues.apache.org/bugzilla/show_bug.cgi?id=54906
Better error message for ConcurrentModificationException when checking for memory leaks and continue with remaining checks.
Based on a patch by NateC.

git-svn-id: https://svn.apache.org/repos/asf/tomcat/tc7.0.x/trunk@1479177 13f79535-47bb-0310-9956-ffa450edef68