Add IEEE 128-bit overload comparison built-in functions.

Add IEEE 128-bit overload comparison built-in functions.

This patch adds support for overloading the IEEE 128-bit comparison built-in
functions bewteeen KFmode and TFmode arguments.

2022-08-01   Michael Meissner  <meissner@linux.ibm.com>

gcc/

	* config/rs6000/rs6000-builtins.def
	(__builtin_vsx_scalar_cmp_exp_qp_eq_kf): Rename KFmode comparison
	built-in functions to have a KF suffix to allow overloading.
	(__builtin_vsx_scalar_cmp_exp_qp_gt_kf): Likewise.
	(__builtin_vsx_scalar_cmp_exp_qp_lt_kf): Likewise.
	(__builtin_vsx_scalar_cmp_exp_qp_unordered_kf): Likewise.
	(__builtin_vsx_scalar_cmp_exp_qp_eq_tf): Add TFmode comparison
	built-in functions.
	(__builtin_vsx_scalar_cmp_exp_qp_gt_tf): Likewise.
	(__builtin_vsx_scalar_cmp_exp_qp_lt_tf): Likewise.
	(__builtin_vsx_scalar_cmp_exp_qp_unordered_tf): Likewise.
	* config/rs6000/rs6000-overload.def
	(__builtin_vec_scalar_cmp_exp_eq): Add TFmode overloaded
	functions.
	(__builtin_vec_scalar_cmp_exp_gt): Likewise.
	(__builtin_vec_scalar_cmp_exp_lt): Likewise.
	(__builtin_vec_scalar_cmp_exp_unordered): Likewise.