Fix timedemo on SDL1

Source/engine/demomode.cpp

@@ -265,8 +265,8 @@ bool LoadDemoMessages(int i)
 			case 0x100: // SDL_QUIT
 				break;
 			default:
-				if (eventType < SDL_USEREVENT) {
-					app_fatal(StrCat("Unknown event ", static_cast<uint32_t>(eventType)));
+				if (eventType < 0x8000) { // SDL_USEREVENT
+					app_fatal(StrCat("Unknown event ", eventType));
 				}
 				break;
 			}

Source/utils/display.cpp

@@ -497,6 +497,8 @@ SDL_Surface *GetOutputSurface()
 bool OutputRequiresScaling()
 {
 #ifdef USE_SDL1
+	if (HeadlessMode)
+		return false;
 	return gnScreenWidth != GetOutputSurface()->w || gnScreenHeight != GetOutputSurface()->h;
 #else // SDL2, scaling handled by renderer.
 	return false;