i386: Fix up builtins used in avx512bf16vlintrin.h [PR108881]

i386: Fix up builtins used in avx512bf16vlintrin.h [PR108881]

The builtins used in avx512bf16vlintrin.h implementation need both
avx512bf16 and avx512vl ISAs, which the header ensures for them, but
the builtins weren't actually requiring avx512vl, so when used by hand
with just -mavx512bf16 -mno-avx512vl it resulted in ICEs.

Fixed by adding OPTION_MASK_ISA_AVX512VL to their BDESC.

2023-02-24  Jakub Jelinek  <jakub@redhat.com>

	PR target/108881
	* config/i386/i386-builtin.def (__builtin_ia32_cvtne2ps2bf16_v16bf,
	__builtin_ia32_cvtne2ps2bf16_v16bf_mask,
	__builtin_ia32_cvtne2ps2bf16_v16bf_maskz,
	__builtin_ia32_cvtne2ps2bf16_v8bf,
	__builtin_ia32_cvtne2ps2bf16_v8bf_mask,
	__builtin_ia32_cvtne2ps2bf16_v8bf_maskz,
	__builtin_ia32_cvtneps2bf16_v8sf_mask,
	__builtin_ia32_cvtneps2bf16_v8sf_maskz,
	__builtin_ia32_cvtneps2bf16_v4sf_mask,
	__builtin_ia32_cvtneps2bf16_v4sf_maskz,
	__builtin_ia32_dpbf16ps_v8sf, __builtin_ia32_dpbf16ps_v8sf_mask,
	__builtin_ia32_dpbf16ps_v8sf_maskz, __builtin_ia32_dpbf16ps_v4sf,
	__builtin_ia32_dpbf16ps_v4sf_mask,
	__builtin_ia32_dpbf16ps_v4sf_maskz): Require also
	OPTION_MASK_ISA_AVX512VL.

	* gcc.target/i386/avx512bf16-pr108881.c: New test.