message: Fix size of marshalled BP buffer
diff: @@ -158,8 +158,7 @@ void SstWriter::EndStep()
  m_BP3Serializer->AggregateCollectiveMetadata(
  m_MPIComm, m_BP3Serializer->m_Metadata, true);
  BP3DataBlock *newblock = new BP3DataBlock;
  - newblock->metadata.DataSize =
  - m_BP3Serializer->m_Metadata.m_Buffer.size();
  + newblock->metadata.DataSize = m_BP3Serializer->m_Metadata.m_Position;
  newblock->metadata.block = m_BP3Serializer->m_Metadata.m_Buffer.data();
  newblock->data.DataSize = m_BP3Serializer->m_Data.m_Buffer.size();
  newblock->data.block = m_BP3Serializer->m_Data.m_Buffer.data();
  