sh.c (shiftcosts): Return MAX_COST when the first operand is CONST_INT.

	* config/sh/sh.c (shiftcosts): Return MAX_COST when the first
	operand is CONST_INT.  Take COSTS_N_INSNS into account.
	(sh_rtx_costs): Don't apply COSTS_N_INSNS to the return value
	of shiftcosts.

From-SVN: r184865