Demomode: Set scancode for keyboard events

We were previously not setting it all which was incorrect but did not
cause any issues because we had not used it. We do check scancode for
the debug console key. This caused a sanitizer warning when running the
demo in debug mode.

Source/engine/demomode.cpp

@@ -270,6 +270,7 @@ bool CreateSdlEvent(const DemoMsg &dmsg, SDL_Event &event, uint16_t &modState)
 	case DemoMsg::KeyUpEvent:
 		event.type = type == DemoMsg::KeyDownEvent ? SDL_KEYDOWN : SDL_KEYUP;
 		event.key.state = type == DemoMsg::KeyDownEvent ? SDL_PRESSED : SDL_RELEASED;
+		event.key.keysym.scancode = SDL_GetScancodeFromKey(dmsg.key.sym);
 		event.key.keysym.sym = dmsg.key.sym;
 		event.key.keysym.mod = dmsg.key.mod;
 		return true;