RFR: JDK-8130063: Refactoring tmtools jstat and jstack tests to jtreg

[Alexander Kulyakhtin]

Hi,

Could you, please, review the following test-only change

CR: https://bugs.openjdk.java.net/browse/JDK-8130063 "Refactoring tmtools jstat and jstack tests to jtreg"
WebRev: http://cr.openjdk.java.net/~akulyakh/8130063_01/

Before the change we had a set of tests verifying the correctness of jstat and jstack tools output in various scenarios.

Those tests have been implemented by means of an internal framework, which sometimes worked unstable, resulting in false nightly failures. 
The functionality, which the tests verify, fully belongs to the open JDK. 

We are refactoring a subset of the tests to use jtreg as the test framework. In this way we are able to avoid some of the false failures of the old framework. 
We are also moving the tests to the Open JDK as they verify the open functionality only.

For the similar refactoring of the remaining java tools tests, a separate JEP is going to be submitted.

The changes have been pre-reviewed internally, the reviewers are CC'ed.

Best regards,
Alexander