Supporting expected results for the jtreg test runner.

This is necessary to suppress false positives when dalvik
intentionally differs from the RI. This came up in the fix
for issue 2224903.

Also adding additional features to the jtreg runner to make
it useful as an iterative development tool:
 - debugger support, to debug through running tests
 - verbose output, to aid in diagnosing hangs

Also adding a few ".expected" files for known test failures.
Hopefully this is scalable.

Renaming Run to TestRun and extracting Result as a top-level enum.
14 files changed