IVOPTS: make comp_cost in a more c++ fashion.

	* tree-ssa-loop-ivopts.c (comp_cost::infinite_cost_p): New
	function.
	(operator+): Likewise.
	(operator-): Likewise.
	(comp_cost::operator+=): Likewise.
	(comp_cost::operator-=): Likewise.
	(comp_cost::operator/=): Likewise.
	(comp_cost::operator*=): Likewise.
	(operator<): Likewise.
	(operator==): Likewise.
	(operator<=): Likewise.
	(new_cost): Remove.
	(infinite_cost_p): Likewise.
	(add_costs): Likewise.
	(sub_costs): Likewise.
	(compare_costs): Likewise.
	(set_group_iv_cost): Use the newly introduced functions.
	(get_address_cost): Likewise.
	(get_shiftadd_cost): Likewise.
	(force_expr_to_var_cost): Likewise.
	(split_address_cost): Likewise.
	(ptr_difference_cost): Likewise.
	(difference_cost): Likewise.
	(get_computation_cost_at): Likewise.
	(determine_group_iv_cost_generic): Likewise.
	(determine_group_iv_cost_address): Likewise.
	(determine_group_iv_cost_cond): Likewise.
	(autoinc_possible_for_pair): Likewise.
	(determine_group_iv_costs): Likewise.
	(cheaper_cost_pair): Likewise.
	(iv_ca_recount_cost): Likewise.
	(iv_ca_set_no_cp): Likewise.
	(iv_ca_set_cp): Likewise.
	(iv_ca_cost): Likewise.
	(iv_ca_new): Likewise.
	(iv_ca_dump): Likewise.
	(iv_ca_narrow): Likewise.
	(iv_ca_prune): Likewise.
	(iv_ca_replace): Likewise.
	(try_add_cand_for): Likewise.
	(try_improve_iv_set): Likewise.
	(find_optimal_iv_set): Likewise.

From-SVN: r236785