RFR (S): 8222534: VerifyBeforeExit is not honored when System.exit is called

[David Holmes]

Bug: https://bugs.openjdk.java.net/browse/JDK-8222534
Webrev: http://cr.openjdk.java.net/~dholmes/8222534/webrev/

Stefan noticed that VerifyBeforeExit was not honoured when a Java 
application terminates via System.exit.

Examination of the exit code sequences revealed four differences between 
an exit due to the last non-daemon thread terminating (handled via 
jni_DestroyJavaVM) and a call to System.exit() (handled via JVM_Halt()). 
There are four missing actions on the System.exit() path:

- No processing of VerifyBeforeExit
- No XML logging before exit
- No LogConfiguration::finalize()
- No IdealGraphPrinter::clean_up()

The first three have now been added at the appropriate point. 
VerifyBefore exit was the main omission. The compiler team  (i.e. 
Vladimir K.) indicated they'd also like the XML logging. And the 
LogConfiguration::finalize while possibly not essential avoids any doubt 
as to whether buffered log output may get lost.

The IdealGraphPrinter::cleanup was deemed unnecessary due to the fact 
the process is being blown away anyway.

The bug report contains a lot of details on the exit sequences including 
a side-by-side comparison in the attached pdf, showing the relative 
positioning of each action and that the correct order has been maintained.

The vm_exit() code affects a number of "abrupt" exit paths in the VM, 
not just JVM_Halt, and this is discussed in the bug report as well. In 
short the addition of the missing actions should not cause any issues.

Testing:
  - some manual checking of exit paths and whether new code was executed
  - all hotspot/jtreg/gc tests with -XX:+VerifyBeforeExit added
  - mach5 tiers 1-3

Thanks,
David