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

[Mandy Chung]

Webrev at:
http://cr.openjdk.java.net/~mchung/jdk8/webrevs/8027351/webrev.00/

This fixes the finalization implementation to invoke the finalize method 
via shared secret so that it will call the same method as the bytecode 
invocation.

The current implementation uses JNI_GetMethodID to find the finalize 
method of a given instance. JNI_GetMethodID returns the private finalize 
method which gets invoked during finalization (which is different than 
the method looked up via invokevirtual).  If there is a static method 
matching the name and descriptor, it will throw NoSuchMethodError even 
if the base class has a matching instance method.  JDK-8027270 is filed 
for this JNI_GetMethodID issue.

This change replaces the JNI call to the finalize method with the shared 
secret as Jeroen suggests [1].  This will resolve this bug independent 
of JDK-8027270 and also avoid the overhead of the JNI calls.

The behavioral change with this fix should rarely impact any existing 
application.  It would only impact code that defines a finalize method 
in a base class and also a private finalize method in a subclass.  The 
only way to have a private finalize method is to write to the bytecode 
directly.

thanks
Mandy
P.S. I would love to use Martin's beloved GcFinalization utility that we 
can extend our testlibrary in the future.  The new regression test is 
simple enough that a counter would do its work.

[1] 
http://weblog.ikvm.net/PermaLink.aspx?guid=87432f77-7e58-4f37-9f6d-d5bac453c7d6
[2] https://bugs.openjdk.java.net/browse/JDK-8027351