message: Enable simd insert and extract tests
  Working since rust-lang/stdarch#876
  Fixes
diff: @@ -144,9 +144,8 @@ unsafe fn test_simd() {
  test_mm_cvtepi8_epi16();
  test_mm_cvtsi128_si64();
  - // FIXME(#666) implement `#[rustc_arg_required_const(..)]` support
  - //test_mm_extract_epi8();
  - //test_mm_insert_epi16();
  + test_mm_extract_epi8();
  + test_mm_insert_epi16();
  let mask1 = _mm_movemask_epi8(dbg!(_mm_setr_epi8(255u8 as i8, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0)));
  assert_eq!(mask1, 1);
  