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

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

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

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

gcc/

	* config/rs6000/rs6000-builtins.def
	(__builtin_addf128_round_to_odd_kf): Rename KFmode round to odd
	built-in functions with a KF suffix to allow overloading.
	(__builtin_divf128_round_to_odd_kf): Likewise.
	(__builtin_fmaf128_round_to_odd_kf): Likewise.
	(__builtin_mulf128_round_to_odd_kf): Likewise.
	(__builtin_sqrtf128_round_to_odd_kf): Likewise.
	(__builtin_subf128_round_to_odd_kf): Likewise.
	(__builtin_truncf128_round_to_odd_kf): Likewise.
	(__builtin_addf128_round_to_odd_tf): Add TFmode round to odd
	built-in functions.
	(__builtin_fmaf128_round_to_odd_tf): Likewise.
	(__builtin_mulf128_round_to_odd_tf): Likewise.
	(__builtin_sqrtf128_round_to_odd_tf): Likewise.
	(__builtin_subf128_round_to_odd_tf): Likewise.
	(__builtin_truncf128_round_to_odd_tf): Likewise.
	* config/rs6000/rs6000-overload.def
	(__builtin_addf128_round_to_odd): Make IEEE 128-bit round to odd
	built-in functions overloaded.
	(__builtin_divf128_round_to_odd): Likewise.
	(__builtin_fmaf128_round_to_odd): Likewise.
	(__builtin_mulf128_round_to_odd): Likewise.
	(__builtin_sqrtf128_round_to_odd): Likewise.
	(__builtin_subf128_round_to_odd): Likewise.
	(__builtin_truncf128_round_to_odd): Likewise.