message: Fix uninitialized memory in cp_writer.c
diff: @@ -1398,6 +1398,7 @@ void SstWriterClose(SstStream Stream)
  {
  struct _WriterCloseMsg Msg;
  struct timeval CloseTime, Diff;
  + memset(&Msg, 0, sizeof(Msg));
  Msg.FinalTimestep = Stream->LastProvidedTimestep;
  SST_ASSERT_UNLOCKED();
  sendOneToEachReaderRank(Stream, Stream->CPInfo->WriterCloseFormat, &Msg,
  @@ -2015,6 +2016,7 @@ extern void SstInternalProvideTimestep(
  SST_REAFFIRM_LOCKED_AFTER_CONDITION();
  }
  }
  + memset(&TimestepMetaData, 0, sizeof(TimestepMetaData));
  TimestepMetaData.PendingReaderCount = 0;
  while (ArrivingReader)
  {
  