re PR target/84406 ([MSP430] ICE on valid code in find_widening_optab_handler_and_mode, at optabs-query.c:476)

	PR middle-end/84406
	* optabs-query.c (find_widening_optab_handler_and_mode): If from_mode
	is a scalar_int_mode, assert that to_mode is a scalar_int_mode with
	greater precision.  If to_mode is a MODE_PARTIAL_INT, stop the
	search at the associated MODE_INT.

From-SVN: r257858