natPlainSocketImpl.cc: Include IllegalArgumentException.h.

	* java/net/natPlainSocketImpl.cc: Include
	IllegalArgumentException.h.
	(_Jv_recv): New template function.
	(BooleanClass): Removed.
	(read): Use _Jv_recv.
	(setOption): Use Boolean::class$.  Throw exception if object is
	not Boolean or Integer.

From-SVN: r48992