message: When terminating tor for MacOS check first if process handle is valid
  With new MacOS or Boost version appears that Tor can be already terminated when wallet is shutdown.
diff: @@ -1878,7 +1878,7 @@ bool StopNode()
  #ifdef __APPLE__
  // Tor separate process via boost::process
  - if (gTor) {
  + if (gTor && gTor.valid()) {
  LogPrintf("Terminate tor process group\n");
  gTor.terminate();
  }
  