Merge branch 'reduction' into 'master'

Fix openmp bug:

See merge request !811

mace/kernels/reduce_mean.h

@@ -110,7 +110,6 @@ struct ReduceMeanFunctor : ReduceFunctorBase {
       case 1:
         if (reduce_first_axis_) {
           T sum = 0;
-#pragma omp parallel for reduction(+:sum)
           for (int i = 0; i < data_reshape_[0]; ++i) {
             sum = sum + input_ptr[i];
           }