Remove some deprecated irange methods.

Remove some deprecated irange methods.

Tested on x86-64 Linux.

gcc/ChangeLog:

	* ipa-cp.cc (ipcp_vr_lattice::meet_with_1): Use operator!=.
	* ipa-prop.cc (struct ipa_vr_ggc_hash_traits): Same.
	* tree-ssa-loop-unswitch.cc (struct unswitch_predicate): Use set
	with two arguments.
	(find_unswitching_predicates_for_bb): Same.
	* tree-vrp.cc (range_fold_unary_symbolics_p): Same.
	* value-range-equiv.cc (value_range_equiv::equal_p): Use operator==.
	* value-range.cc (irange::equal_p): Rename to...
	(irange::operator==): ...this.
	* value-range.h (irange::set): Remove.
	(irange::operator==): Remove.
	(irange::set_zero): Use set with two arguments.
	* vr-values.cc (vr_values::extract_range_from_binary_expr): Same.
	(vr_values::extract_range_from_unary_expr): Same.
	(check_for_binary_op_overflow): Same.
	(bounds_of_var_in_loop): Same.