JDK-8027351: (ref) Base's class finalize method not invoked if a private finalize method exists in its subclass

[Mandy Chung]

Thank you all for the suggestions.

Before the VM initialization is completed, any agent ought to be careful 
in what things it can do and what shouldn't do.  I think it's reasonable 
to ignore System.runFinalization if it's called at early startup phase.  
I'm unclear if there is any use case that we really require finalization 
to happen before VM is booted (I can imagine other problems may happen). 
I change the runFinalization and runAllFinalizers methods to return if 
it's not booted and also change runFinalizer method to take 
JavaLangAccess to simplify the synchronization instead of caching it in 
the static field.

http://cr.openjdk.java.net/~mchung/jdk8/webrevs/8027351/webrev.02/

David - I decided to leave VM.awaitBooted as it is.  Having the callsite 
to call awaitBooted makes it explicit and clear that it's blocking and 
we will keep SharedSecrets.getJavaLangAccess method consistent with the 
other SharedSecrets methods that they are all getter methods.  If any 
future change calls SharedSecrets.getJavaLangAccess before it's booted, 
it's a little easier to diagnose (NPE vs hangs).

Peter - thanks for the ObjectAccess idea.  I don't think supporting 
finalization to happen before VM is booted buys us anything and I would 
rather keep this change simple.

Mandy