gimple-range-op: Handle sqrt (basic bounds only)

gimple-range-op: Handle sqrt (basic bounds only)

The following patch adds sqrt support (but similarly to sincos, only
dumb basic ranges only).

Will improve this incrementally and sin/cos as well.

2023-04-28  Jakub Jelinek  <jakub@redhat.com>

	* gimple-range-op.cc (class cfn_sqrt): New type.
	(op_cfn_sqrt): New variable.
	(gimple_range_op_handler::maybe_builtin_call): Handle
	CASE_CFN_SQRT{,_FN}.

	* gcc.dg/tree-ssa/range-sqrt.c: New test.
	* gfortran.dg/ieee/ieee_6.f90: Make x volatile to avoid
	ranger optimizing sqrt (-1) call away because it is only used in
	test for whether it returns NaN.