Don't fail old service cleanup

win/winvnc/winvnc.cxx

@@ -170,8 +170,16 @@ static void processParams(int argc, char** argv) {
         i = argc;
 
         // Try to clean up earlier services we've had
-        rfb::win32::unregisterService("WinVNC4");
-        rfb::win32::unregisterService("TigerVNC Server");
+        try {
+          rfb::win32::unregisterService("WinVNC4");
+        } catch (rdr::SystemException) {
+          // Do nothing as we might fail simply because there was no
+          // service to remove
+        }
+        try {
+          rfb::win32::unregisterService("TigerVNC Server");
+        } catch (rdr::SystemException) {
+        }
 
         if (rfb::win32::registerService(VNCServerService::Name,
                                         _T("TigerVNC Server"),