message: Fix UB in CreateVectorOfStructs in case of an empty vector: avoid calling memcpy in this case
diff: @@ -1914,7 +1914,9 @@ class FlatBufferBuilder {
  template<typename T>
  Offset<Vector<const T *>> CreateVectorOfStructs(const T *v, size_t len) {
  StartVector(len * sizeof(T) / AlignOf<T>(), AlignOf<T>());
  + if (len > 0) {
  PushBytes(reinterpret_cast<const uint8_t *>(v), sizeof(T) * len);
  + }
  return Offset<Vector<const T *>>(EndVector(len));
  }
  