MappedByteBuffer.java: (forceImpl...

	* java/nio/MappedByteBuffer.java: (forceImpl, isLoadedImpl, loadImpl,
	unmapImpl):  New dummy methods, to be overridden by subclass.
	(finalize, isLoaded, load, force):  New methods.
	* java/nio/MappedByteBufferImpl.java:  More-or-less rewrite.
	Now works, at least for read mapping.

From-SVN: r78662