i386:: using __bf16 for AVX512BF16 intrinsics

gcc/ChangeLog:

	* config/i386/avx512bf16intrin.h (__attribute__): Change short to bf16.
	(_mm_cvtsbh_ss): Ditto.
	(_mm512_cvtne2ps_pbh): Ditto.
	(_mm512_mask_cvtne2ps_pbh): Ditto.
	(_mm512_maskz_cvtne2ps_pbh): Ditto.
	* config/i386/avx512bf16vlintrin.h (__attribute__): Ditto.
	(_mm256_cvtne2ps_pbh): Ditto.
	(_mm256_mask_cvtne2ps_pbh): Ditto.
	(_mm256_maskz_cvtne2ps_pbh): Ditto.
	(_mm_cvtne2ps_pbh): Ditto.
	(_mm_mask_cvtne2ps_pbh): Ditto.
	(_mm_maskz_cvtne2ps_pbh): Ditto.
	(_mm_cvtness_sbh): Ditto.
	* config/i386/i386-builtin-types.def (V8BF): Add new
	DEF_VECTOR_TYPE for BFmode.
	(V16BF): Ditto.
	(V32BF): Ditto.
	* config/i386/i386-builtin.def (BDESC): Fixed builtins.
	* config/i386/i386-expand.cc (ix86_expand_args_builtin): Changed
	avx512bf16 ix86_builtin_func_type included HI to BF.
	* config/i386/immintrin.h: Add SSE2 depend for avx512bf16.
	* config/i386/sse.md (TARGET_AVX512VL): Changed HI vector to BF
	vector.
	(avx512f_cvtneps2bf16_v4sf): New define_expand.
	(*avx512f_cvtneps2bf16_v4sf): New define_insn.
	(avx512f_cvtneps2bf16_v4sf_maskz):Ditto.
	(avx512f_cvtneps2bf16_v4sf_mask): Ditto.
	(avx512f_cvtneps2bf16_v4sf_mask_1): Ditto.

gcc/testsuite/ChangeLog:

	* gcc.target/i386/avx512bf16-cvtsbh2ss-1.c: Add fpmath option.
	* gcc.target/i386/avx512bf16-vdpbf16ps-2.c: Fixed
	scan-assembler.
	* gcc.target/i386/avx512bf16vl-cvtness2sbh-1.c: Add x/y suffix
	for vcvtneps2bf16.
	* gcc.target/i386/avx512bf16vl-vcvtneps2bf16-1.c: Ditto.