Fix Joysticks on Web.

The html Gamepad API does not support an event-based model, only a polling model for input
(see [here](https://emscripten.org/docs/api_reference/html5.h.html#how-to-use-this-api)).
While mouse and such work without the `SDL_PollEvent` and resulting `SDL_PumpEvents`
call because SDL sets emscripten callbacks that handle the other events,
joysticks will only be connected and updated once, and then not again.

Source/Urho3D/Input/Input.cpp

@@ -409,7 +409,6 @@ void Input::Update()
 
     URHO3D_PROFILE(UpdateInput);
 
-#ifndef __EMSCRIPTEN__
     bool mouseMoved = false;
     if (mouseMove_ != IntVector2::ZERO)
         mouseMoved = true;
@@ -420,6 +419,7 @@ void Input::Update()
     while (SDL_PollEvent(&evt))
         HandleSDLEvent(&evt);
 
+#ifndef __EMSCRIPTEN__
     if (suppressNextMouseMove_ && (mouseMove_ != IntVector2::ZERO || mouseMoved))
         UnsuppressMouseMove();
 #endif