ira-costs.c (find_allocno_class_costs): Work out the maximum allocno_costs value of the classees with the lowest...

gcc/
	* ira-costs.c (find_allocno_class_costs): Work out the maximum
	allocno_costs value of the classees with the lowest total_costs
	value.  Use this to set ALLOCNO_COVER_CLASS_COST here...
	(setup_allocno_cover_class_and_costs): ...rather than here.
	Use the ALLOCNO_COVER_CLASS_COST for all registers in the
	preferred class.

From-SVN: r142117