Make joystick platform code init on demand

This makes joystick support initialize the first time a joystick
function is called, including those gamepad functions that are layered
on top of joystick functions.

Related to #1284.
Related to #1646.

src/win32_window.c

@@ -531,6 +531,9 @@ static LRESULT CALLBACK windowProc(HWND hWnd, UINT uMsg,
 
             case WM_DEVICECHANGE:
             {
+                if (!_glfw.joysticksInitialized)
+                    break;
+
                 if (wParam == DBT_DEVICEARRIVAL)
                 {
                     DEV_BROADCAST_HDR* dbh = (DEV_BROADCAST_HDR*) lParam;