SDL_XINPUT_Enabled() returns false until XInput DLL is successfully loaded

We make sure we initialize XInput first, so that anything checking whether it's enabled gets a valid result based on whether we were able to load it or not.

src/joystick/windows/SDL_xinputjoystick.c

@@ -37,7 +37,7 @@ extern "C" {
 /*
  * Internal stuff.
  */
-static bool s_bXInputEnabled = true;
+static bool s_bXInputEnabled = false;
 
 bool SDL_XINPUT_Enabled(void)
 {