Fix warnings in gcc and clang for missing initializers.

Normally I would disable the warning completely (everywhere), but it's very useful to have.
In this case, the code can be much faster, as it saves having to initialize empty string objects.  So we disable the warning selectively.

src/emucore/EventHandler.cxx

@@ -2784,6 +2784,11 @@ void EventHandler::exitEmulation(bool checkLauncher)
   }
 }
 
+#if defined(__clang__)
+  #pragma clang diagnostic ignored "-Wmissing-field-initializers"
+#elif defined(__GNUC__) || defined(__GNUG__)
+  #pragma GCC diagnostic ignored "-Wmissing-field-initializers"
+#endif
 // - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
 EventHandler::EmulActionList EventHandler::ourEmulActionList = { {
   { Event::Quit,                    "Quit"                                  },