range-op: Implement floating point multiplication fold_range [PR107569]

The following patch implements frange multiplication, including the
special case of x * x.  The callers don't tell us that it is x * x,
just that it is either z = x * x or if (x == y) z = x * y;
For irange that makes no difference, but for frange it can mean
x is -0.0 and y is 0.0 if they have the same range that includes both
signed and unsigned zeros, so we need to assume result could be -0.0.

The patch causes one regression:
+FAIL: gcc.dg/fold-overflow-1.c scan-assembler-times 2139095040 2
but that is already tracked in PR107608 and affects not just the newly
added multiplication, but addition and other floating point operations
(and doesn't seem like a ranger bug but dce or whatever else).

2022-11-12  Jakub Jelinek  <jakub@redhat.com>

	PR tree-optimization/107569
	PR tree-optimization/107591
	* range-op.h (range_operator_float::rv_fold): Add relation_kind
	argument.
	* range-op-float.cc (range_operator_float::fold_range): Name
	last argument trio and pass trio.op1_op2 () as last argument to
	rv_fold.
	(range_operator_float::rv_fold): Add relation_kind argument.
	(foperator_plus::rv_fold, foperator_minus::rv_fold): Likewise.
	(foperator_mult): New class.
	(floating_op_table::floating_op_table): Use foperator_mult for
	MULT_EXPR.