message: fix reading block signature while accepting blocks
diff: @@ -2630,6 +2630,7 @@ bool static ProcessMessage(CNode* pfrom, const std::string& strCommand, CDataStr
  for (unsigned int n = 0; n < nCount; n++) {
  vRecv >> headers[n];
  ReadCompactSize(vRecv); // ignore tx count; assume it is 0.
  + ReadCompactSize(vRecv); // needed for vchBlockSig.
  }
  // Headers received via a HEADERS message should be valid, and reflect
  