message: Allow ComplexAbs Op on mobile platforms
  Seems like it was disabled long time ago before open-sourcing Tensorflow.
  I think disabling it is no longer necessary.
  Works now on Android. Could anyone check on iOS?
  Somewhat related issue:
diff: @@ -18,9 +18,7 @@ limitations under the License.
  namespace tensorflow {
  REGISTER5(UnaryOp, CPU, "Abs", functor::abs, float, Eigen::half, double, int32,
  int64);
  -#if !defined(IS_MOBILE_PLATFORM)
  REGISTER2(UnaryOp, CPU, "ComplexAbs", functor::abs, complex64, complex128);
  -#endif
  #if GOOGLE_CUDA
  REGISTER4(UnaryOp, GPU, "Abs", functor::abs, float, Eigen::half, double, int64);
  