remove spoofed SDL_HelperWindow when SDL_VIDEO is off

(cherry picked from commit 0f061ff154)

src/haptic/windows/SDL_dinputhaptic.c

@@ -31,11 +31,7 @@
 /*
  * External stuff.
  */
-#ifdef SDL_VIDEO_DRIVER_WINDOWS
 extern HWND SDL_HelperWindow;
-#else
-static const HWND SDL_HelperWindow = NULL;
-#endif
 
 /*
  * Internal stuff.

src/joystick/windows/SDL_dinputjoystick.c

@@ -40,11 +40,7 @@
 #define CONVERT_MAGNITUDE(x) (((x)*10000) / 0x7FFF)
 
 // external variables referenced.
-#ifdef SDL_VIDEO_DRIVER_WINDOWS
 extern HWND SDL_HelperWindow;
-#else
-static const HWND SDL_HelperWindow = NULL;
-#endif
 
 // local variables
 static bool coinitialized = false;