7132204: Default testset in JPRT should not run all tests

[Alan Bateman]

Kelly - this is a change to the JPRT configuration to dial-down the 
number of test targets that are run by default. It also adds a new 
testset, called "core" that runs all langtools and jdk excepts except 
for the AWT/Swing/client tests. A couple of persistent offenders added 
to the ProblemList too. The webrev with the changes is here:

http://cr.openjdk.java.net/~alanb/7132204/webrev/

Thanks,

Alan.