Add extension and agent for dumping internal jvmti plugin data.

When debugging openjdkjvmti plugin issues it can be useful to dump
internal state somewhere it can be examined. This adds a new extension
method that will let agents get a view of the deopt state of the
plugin and an agent that prints this information to LOG(INFO) on
SIGQUIT.

Test: ./test.py --host
Change-Id: Ia265a5bcca31a2df5ac930ddc2ecffb57d3db911