RFR: JDK-8145788: JVM crashes with -XX:+EnableTracing

[Yasumasa Suenaga]

Hi all,

I encountered JVM crash when I passed -XX:+EnableTracing. 

 I checked core image, it crashed in EventBooleanFlagChanged::writeEvent() 
 which is called by Arguments::apply_ergo() because thread had not been 
 initialized. (JVM seems to log changing GC algorithm to G1.) 

 writeEvent() uses ResourceMark. Default constructor of ResourceMark uses 
 ResourceArea in current thread. So ResourceMark in writeEvent() should 
 pass valid ResourceArea.

I think this issue is in traceEventClasses.xsl .
However, my environment (GCC 5.3.1 on Fedora23) cannot build it because
-Werror=maybe-uninitialized was occurred.
So I also fixed them together.

I've uploaded webrev. Could you review it?
  http://cr.openjdk.java.net/~ysuenaga/JDK-8145788/webrev.00/

I'm jdk9 committer, however I cannot access JPRT.
So I need a sponsor.


Thanks,

Yasumasa