Split gimple range folding with ranges into a stand alone class.

Introduces fold_using_range which folds any kind of gimple statement by
querying argument ranges thru a generic range_query.
This pulls all the statement processing into a client neutral location.

	* gimple-range.cc (fur_source::get_operand): New.
	(gimple_range_fold): Delete.
	(fold_using_range::fold_stmt): Move from gimple_ranger::calc_stmt.
	(fold_using_range::range_of_range_op): Move from gimple_ranger.
	(fold_using_range::range_of_address): Ditto.
	(fold_using_range::range_of_phi): Ditto.
	(fold_using_range::range_of_call): Ditto.
	(fold_using_range::range_of_builtin_ubsan_call): Move from
	range_of_builtin_ubsan_call.
	(fold_using_range::range_of_builtin_call): Move from
	range_of_builtin_call.
	(gimple_ranger::range_of_builtin_call): Delete.
	(fold_using_range::range_of_cond_expr): Move from gimple_ranger.
	(gimple_ranger::fold_range_internal): New.
	(gimple_ranger::range_of_stmt): Use new fold_using_range API.
	(fold_using_range::range_of_ssa_name_with_loop_info): Move from
	gimple_ranger.  Improve ranges of SSA_NAMES when possible.
	* gimple-range.h (gimple_ranger): Remove various range_of routines.
	(class fur_source): New.
	(class fold_using_range): New.
	(fur_source::fur_source): New.
	(fold_range): New.
	* vr-values.c (vr_values::extract_range_basic): Use fold_using_range
	instead of range_of_builtin_call.