Clean up any opened joysticks during SDL_JoystickQuit().

Otherwise, these leak memory and maybe operating system handles.

src/joystick/SDL_joystick.c

@@ -403,9 +403,22 @@ SDL_JoystickClose(SDL_Joystick * joystick)
 void
 SDL_JoystickQuit(void)
 {
+    const int numsticks = SDL_numjoysticks;
+    int i;
+
     /* Stop the event polling */
     SDL_numjoysticks = 0;
 
+    SDL_assert( (SDL_joysticks == NULL) == (numsticks == 0) );
+
+    for (i = 0; i < numsticks; i++) {
+        SDL_Joystick *stick = SDL_joysticks[i];
+        if (stick && (stick->ref_count >= 1)) {
+            stick->ref_count = 1;
+            SDL_JoystickClose(stick);
+        }
+    }
+
     /* Quit the joystick setup */
     SDL_SYS_JoystickQuit();
     if (SDL_joysticks) {