LUCENE-4737: be more verbose and print stdout/stderr when a nested test fails. I suspect all these are related to thread leaks on J9 which I cannot reproduce but this should reveal the cause of the problem.

git-svn-id: https://svn.apache.org/repos/asf/lucene/dev/trunk@1440882 13f79535-47bb-0310-9956-ffa450edef68