Implement vrange::supports_type_p.

Implement vrange::supports_type_p.

[I have conservatively assumed that both the loop-ch and loop-unswitch
passes, which also use the ranger, only support integers and pointers.
If the goal is to handle other types as well, irange::supports_p()
should be Value_Range::supports_type_p(), and any uses of
int_range_max should be converted to Value_Range.  I can help in the
conversion if you'd like.]

As discussed, this patch disambiguates the use of supports_type_p
throughout, as what ranger supports is a totally different question
than what a given range variant (irange, frange, etc) supports.

Unfortunately we need both a static method and a virtual method, and
they can't be named the same.  The uses are documented in the vrange
class:

+// To query what types ranger and the entire ecosystem can support,
+// use Value_Range::supports_type_p(tree type).  This is a static
+// method available independently of any vrange object.
+//
+// To query what a given vrange variant can support, use:
+//    irange::supports_p ()
+//    frange::supports_p ()
+//    etc
+//
+// To query what a range object can support, use:
+//    void foo (vrange &v, irange &i, frange &f)
+//    {
+//     if (v.supports_type_p (type)) ...
+//     if (i.supports_type_p (type)) ...
+//     if (f.supports_type_p (type)) ...
+//    }

The value_range_equiv::supports_p() method can be use to determine
what legacy VRP supports, as irange::supports_p() will no longer be
applicable in the evrp analyzer code base once irange and prange are
split.

Tested on x86-64 Linux.

gcc/ChangeLog:

	* gimple-range-edge.cc (gimple_outgoing_range_stmt_p): Adjust for
	an object level supports_type_p for irange and a static
	Value_Range::supports_type_p.
	* gimple-range-fold.cc (fold_using_range::range_of_range_op): Same.
	(fold_using_range::range_of_address): Same.
	(fold_using_range::range_of_builtin_call): Same.
	* gimple-range-fold.h (gimple_range_type): Same.
	(gimple_range_ssa_p): Same.
	* gimple-range-path.cc (path_range_query::internal_range_of_expr):
	Same.
	(path_range_query::range_of_stmt): Same.
	(path_range_query::add_to_imports): Same.
	* gimple-range.cc (gimple_ranger::range_on_edge): Same.
	(gimple_ranger::export_global_ranges): Same.
	* gimple-ssa-evrp-analyze.cc
	(evrp_range_analyzer::record_ranges_from_phis):  Same.
	* range-op.cc (range_operator::wi_fold): Same.
	(range_operator::fold_range): Same.
	* tree-ssa-loop-ch.cc (entry_loop_condition_is_static): Same.
	* tree-ssa-loop-unswitch.cc (struct unswitch_predicate): Same.
	(evaluate_control_stmt_using_entry_checks): Same.
	* tree-ssa-threadedge.cc
	(hybrid_jt_simplifier::compute_ranges_from_state): Same.
	* tree-vrp.cc (supported_types_p): Same.
	* value-query.cc (range_query::value_of_expr): Same.
	(range_query::value_on_edge): Same.
	(range_query::value_of_stmt): Same.
	(range_query::get_tree_range): Same.
	(get_range_global): Same.
	(global_range_query::range_of_expr): Same.
	* value-range-equiv.h (class value_range_equiv): Same.
	* value-range.cc (irange::supports_type_p): Same.
	(unsupported_range::supports_type_p): Same.
	* value-range.h (enum value_range_discriminator): Same.
	(Value_Range::init): Same.
	(Value_Range::supports_type_p): Same.
	(irange::supports_type_p): Same.
	(irange::supports_p): Same.
	(vrange::supports_type_p): Same.
	(vrange_allocator::alloc_vrange): Same.