AVX10.2 ymm rounding: Support vcvttph2{,u}{dq,qq,w} intrins

gcc/ChangeLog:

	* config/i386/avx10_2roundingintrin.h: New intrins.
	* config/i386/i386-builtin.def (BDESC): Add new builtins.
	* config/i386/sse.md (avx512fp16_fix<fixunssuffix>_trunc<mode>2<mask_name>):
	Extend round control for 256bit.
	(unspec_avx512fp16_fix<vcvtt_uns_suffix>_trunc<mode>2<mask_name>):
	Ditto.
	(avx512fp16_fix<fixunssuffix>_trunc<mode>2<mask_name><round_saeonly_name>):
	Add condition check.
	* config/i386/subst.md
	(round_saeonly_mode_condition): Add V16HI check for 256bit.

gcc/testsuite/ChangeLog:

	* gcc.target/i386/avx-1.c: Add new builtin test.
	* gcc.target/i386/sse-13.c: Ditto.
	* gcc.target/i386/sse-14.c: Ditto.
	* gcc.target/i386/sse-22.c: Add new macro test.
	* gcc.target/i386/sse-23.c: Ditto.
	* gcc.target/i386/avx10_2-rounding-2.c: Add test.