(close): Use native implementation.
	(finalize): New method.

	* java/net/PlainSocketImpl.java (finalize): New method.

	* java/net/natPlainDatagramSocketImpl.cc
	(java/io/FileDescriptor.h): Don't include.
	(close): Implement method here.
	(create): Don't assign fd.

	* java/net/natPlainSocketImpl.cc
	(java/io/FileDescriptor.h): Don't include.
	(create): Don't assign fd.
	(accept): Likewise.
	(close): Synchronize.

From-SVN: r51492