message: system contract compilation fix after merge
diff: @@ -619,18 +619,6 @@ inline datastream<Stream>& operator>>(datastream<Stream>& ds, checksum160& cs) {
  return ds;
  }
  -template<typename Stream>
  -inline datastream<Stream>& operator<<(datastream<Stream>& ds, const checksum256& cs) {
  - ds.write((const char*)&cs, sizeof(cs));
  - return ds;
  -}
  -
  -template<typename Stream>
  -inline datastream<Stream>& operator>>(datastream<Stream>& ds, checksum256& cs) {
  - ds.read((char*)&cs, sizeof(cs));
  - return ds;
  -}
  -
  template<typename Stream>
  inline datastream<Stream>& operator<<(datastream<Stream>& ds, const checksum512& cs) {
  ds.write((const char*)&cs, sizeof(cs));
  