[lldb] [Process/gdb-remote] Fix defaulting signal to invalid in action list

[mgorny]

Summary

Fix processing of "C" packet with signal for the whole process to
default signal value for action list to LLDB_INVALID_SIGNAL_NUMBER
rather than 0.

lldb/source/Plugins/Process/gdb-remote/GDBRemoteCommunicationServerLLGS.cpp

if (packet.GetBytesLeft() > 0) {
     // FIXME add continue at address support for $C{signo}[;{continue-address}].
     if (*packet.Peek() == ';')
       return SendUnimplementedResponse(packet.GetStringRef().data());
     else
       return SendIllFormedResponse(
           packet, "unexpected content after $C{signal-number}");
   }
 
-  ResumeActionList resume_actions(StateType::eStateRunning, 0);
+  ResumeActionList resume_actions(StateType::eStateRunning,
+                                  LLDB_INVALID_SIGNAL_NUMBER);
   Status error;
 
   // We have two branches: what to do if a continue thread is specified (in
   // which case we target sending the signal to that thread), or when we don't
   // have a continue thread set (in which case we send a signal to the
   // process).
 
   // TODO discuss with Greg Clayton, make sure this makes sense.
case '>':
       result += ">";
       break;
     default:
       result += c;
       break;
     }
   }
   return result;
-}
+}