Fixed warning C6340: Mismatch on sign: 'const unsigned short' passed as _Param_(2) when some signed type is required in call to 'SDL_SetError_REAL'.

src/joystick/virtual/SDL_virtualjoystick.c

@@ -119,7 +119,7 @@ SDL_JoystickID SDL_JoystickAttachVirtualInner(const SDL_VirtualJoystickDesc *des
     }
     if (desc->version != SDL_VIRTUAL_JOYSTICK_DESC_VERSION) {
         /* Is this an old version that we can support? */
-        return SDL_SetError("Unsupported virtual joystick description version %d", desc->version);
+        return SDL_SetError("Unsupported virtual joystick description version %u", desc->version);
     }
 
     hwdata = SDL_calloc(1, sizeof(joystick_hwdata));