Fix gcc.dg/lower-subreg-1.c failure, revisited.

[Hans-Peter Nilsson]

> From: Hans-Peter Nilsson <hp@axis.com>
> Date: Sun, 8 Jul 2012 01:02:34 +0200

	PR rtl-optimization/53176
> 	* rtlanal.c (rtx_cost): Adjust default cost for X with a
> 	UNITS_PER_WORD factor for all X according to the size of
> 	its mode, not just for SUBREGs with untieable modes.
> 	Handle SET.  Use factor * factor for MULT, DIV, UDIV,
> 	MOD, UMOD.

Approved (IRL by RTH), committed.

brgds, H-P