message: fix member variable type for bcast
diff: @@ -168,7 +168,7 @@ class OSPRAY_MPI_INTERFACE Bcast : public Collective
  private:
  std::shared_ptr<ospcommon::utility::ArrayView<uint8_t>> buffer;
  - int count;
  + size_t count;
  int typeSize;
  MPI_Datatype datatype;
  int root;
  