message: Restrict detect_dotprod to linux.
  We're debugging further trouble on iOS even with the current
  __APPLE__ check.
diff: @@ -19,7 +19,9 @@ limitations under the License.
  // EXC_BAD_INSTRUCTION is actually a different signal?
  // Anyway, we don't need this code on Apple devices at the moment, as none of
  // them supports dot-product instructions at the moment.
  -#if defined __aarch64__ && !defined __APPLE__
  +// In fact, for the moment, we only care about Linux, so restricting to it
  +// limits our risk.
  +#if defined __aarch64__ && defined __linux__
  #define RUY_IMPLEMENT_DETECT_DOTPROD
  #endif
  