re PR middle-end/52940 (conversion from MODE_PARTIAL_INT uses sign extension for...

re PR middle-end/52940 (conversion from MODE_PARTIAL_INT uses sign extension for unsigned types)

	PR middle-end/52940
	* machmode.h (CLASS_HAS_WIDER_MODES_P): True for MODE_PARTIAL_INT.
	* expr.c (convert_move): Honor unsignedp when extending partial int
	modes.
	* genmodes.c (complete_mode): Don't clear component field of partial
	int modes.
	(emit_mode_inner): Don't emit it however.
	(calc_wider_mode): Partial int modes widen to their component.

From-SVN: r186877