(11) RFR (XS): 8205966: [testbug] New Nestmates JDI test times out with Xcomp on sparc

[David Holmes]

Bug: https://bugs.openjdk.java.net/browse/JDK-8205966
webrev: http://cr.openjdk.java.net/~dholmes/8205966/webrev/

One of the @run variants was taking around 15x longer to execute. That 
variant uses the InMemoryJavaCompiler which involves a lot of classes 
and code execution. The test was enabling method entry event generation 
for all of main, resulting in the massive slowdown.

The fix is to add a new breakpoint() function that gets called after the 
in-memory compilation setup is done, and we initially run the test to 
that point before enabling the events.

The problem @run now only takes 2x the other tests and so should avoid 
the timeouts.

Testing: mach5 tier4 solaris-sparc
          mach5 tier 1-3

Thanks,
David