8028478: Re-visit JPRT testsets to make it easier to run subsets of the tests

[Alan Bateman]

This is an update to the "test sets" used by the build+test system used 
in Oracle (and so not interesting for OpenJDK). It is basically a 
refresh of the testsets so that it is simple to select a default, core, 
svc, pit or all tests when submitting a job. I have already discussed 
this update with a number of people so I don't require additional 
reviews (but additional reviewers are always welcome).

As part of the change I have updated the jdk/test make file to recognize 
core_* and svc_* targets. This allows test groups (defined in 
TEST.groups) to be selected when using the test make target, eg: "make 
test TESTS=svc_tools" to run the tests for the serviceability tools.

The webrev with the changes is here:
   http://cr.openjdk.java.net/~alanb/8028478/webrev/

-Alan.