RFR (S): 8213397: Stack dump should show more clearly when a thread is blocked on a class initialization monitor

[David Holmes]

Bug: https://bugs.openjdk.java.net/browse/JDK-8213397
webrev: http://cr.openjdk.java.net/~dholmes/8213397/webrev/

Please review this simple enhancement to improve the stack trace 
information when a thread is blocked doing a (logical) Object.wait on 
the monitor associated with Class static initialization.

Details are in the bug report but basically we record, in a thread-local 
variable, the name of the class before the "wait" and clear it after, 
thus allowing the stack dump code to query it if it appears we may be in 
that situation.

In InstanceKlass::initialize_impl I also refactored the code a tiny bit 
to make use of the JavaThread reference to the current thread.

A new test using jstack was also added.

Testing:
   - mach5 tiers 1 - 3
   - the new test on Windows/Linux/OSX x86 and Solaris sparc, in regular 
and Xcomp mode
   - All jstack/stack-dump using tests I could see (linux x64):
     - runtime/Thread
     - serviceability/sa/
     - serviceability/tmtools/jstack/
     - vmTestbase/nsk/jvmti/scenarios/sampling/
     - vmTestbase/nsk/jvmti/MonitorWaited/ .
     - vmTestbase/nsk/jvmti/GetOwnedMonitorInfo/

Thanks,
David