RFR 8215299: Remove G1CMTask::should_exit_termination()'s undesirable side-effect

[zgu at redhat.com]

Hi Kim,

Thanks for the review. 

Please see updated webrev based on your suggestion:
http://cr.openjdk.java.net/~zgu/JDK-8215299/webrev.03/index.html


> Looks good, but I’d like to see more testing of something this
> “core”, especially a bit of stress testing.
> The submit tests are more at the level of “smoke” tests.

Besides submit tests, I also ran hotspot_gc tests on Linux 64, which
contains stress tests.

This cycle, I also ran vmTestbase_vm_gc tests on Linux 64.

Thanks,

-Zhengyu

> 
> Given that most callers of regular_clock_call now conditionally call
> set_has_aborted, a helper function to encapsulate that might be nice.
>