AVX512FP16: Add vaddsh/vsubsh/vmulsh/vdivsh.

AVX512FP16: Add vaddsh/vsubsh/vmulsh/vdivsh.

gcc/ChangeLog:

	* config/i386/avx512fp16intrin.h (_mm_add_sh): New intrinsic.
	(_mm_mask_add_sh): Likewise.
	(_mm_maskz_add_sh): Likewise.
	(_mm_sub_sh): Likewise.
	(_mm_mask_sub_sh): Likewise.
	(_mm_maskz_sub_sh): Likewise.
	(_mm_mul_sh): Likewise.
	(_mm_mask_mul_sh): Likewise.
	(_mm_maskz_mul_sh): Likewise.
	(_mm_div_sh): Likewise.
	(_mm_mask_div_sh): Likewise.
	(_mm_maskz_div_sh): Likewise.
	(_mm_add_round_sh): Likewise.
	(_mm_mask_add_round_sh): Likewise.
	(_mm_maskz_add_round_sh): Likewise.
	(_mm_sub_round_sh): Likewise.
	(_mm_mask_sub_round_sh): Likewise.
	(_mm_maskz_sub_round_sh): Likewise.
	(_mm_mul_round_sh): Likewise.
	(_mm_mask_mul_round_sh): Likewise.
	(_mm_maskz_mul_round_sh): Likewise.
	(_mm_div_round_sh): Likewise.
	(_mm_mask_div_round_sh): Likewise.
	(_mm_maskz_div_round_sh): Likewise.
	* config/i386/i386-builtin-types.def: Add corresponding builtin types.
	* config/i386/i386-builtin.def: Add corresponding new builtins.
	* config/i386/i386-expand.c
	(ix86_expand_round_builtin): Handle new builtins.
	* config/i386/sse.md (VF_128): Change description.
	(<sse>_vm<plusminus_insn><mode>3<mask_scalar_name><round_scalar_name>):
	Adjust to support HF vector modes.
	(<sse>_vm<multdiv_mnemonic><mode>3<mask_scalar_name><round_scalar_name>):
	Likewise.

gcc/testsuite/ChangeLog:

	* gcc.target/i386/avx-1.c: Add test for new builtins.
	* gcc.target/i386/sse-13.c: Ditto.
	* gcc.target/i386/sse-23.c: Ditto.
	* gcc.target/i386/sse-14.c: Add test for new intrinsics.
	* gcc.target/i386/sse-22.c: Ditto.