(set_clipboard_data): If there's not enough memory

(set_clipboard_data): If there's not enough memory
to put text into clipboard, return 1, as Fw16_set_clipboard_data
expects.  In case of other failures, return 3.
(system_error_msg): New error message.
(Fw16_set_clipboard_data): If set_clipboard_data returns 3, print
system_error_msg.