* fhandler.h (class fhandler_dev_mem): Remove dup method declaration.

	* fhandler.h (class fhandler_dev_mem): Remove dup method declaration.
	* fhandler_clipboard.cc (fhandler_dev_clipboard::dup): Accommodate the
	fact that the entire fhandler gets copied over to the child in
	operator =.
	* fhandler_floppy.cc (fhandler_dev_floppy::dup): Ditto.
	* fhandler_raw.cc (fhandler_dev_raw::dup): Ditto.
	* fhandler_serial.cc (fhandler_serial::dup): Ditto.
	* fhandler_socket.cc (fhandler_socket::dup): Ditto.
	* fhandler_virtual.cc (fhandler_virtual::dup): Ditto.
	* fhandler_mem.cc (fhandler_dev_mem::dup): Ditto.  Remove entirely.