var crypto/sha1.useAVX2

2 uses

	crypto/sha1 (current package)
		sha1block_amd64.go#L15: var useAVX2 = cpu.X86.HasAVX2 && cpu.X86.HasBMI1 && cpu.X86.HasBMI2
		sha1block_amd64.go#L18: 	if useAVX2 && len(p) >= 256 {