[gnome-games] retro-gamepad: Adapt to changes in retro-gtk

[Adrien Plazas <aplazas src gnome org>]

commit 0cd4d8083ec3529aafbf4ceb5b9ab83c0ed7718f
Author: Adrien Plazas <kekun plazas laposte net>
Date:   Sun Nov 19 15:49:28 2017 +0100

    retro-gamepad: Adapt to changes in retro-gtk
    
    Retro.controller.set_rumble_state() is a virtual method now and hence
    must be implemented.

 src/retro/retro-gamepad.vala |    4 ++++
 1 files changed, 4 insertions(+), 0 deletions(-)
---
diff --git a/src/retro/retro-gamepad.vala b/src/retro/retro-gamepad.vala
index abd7b88..8791707 100644
--- a/src/retro/retro-gamepad.vala
+++ b/src/retro/retro-gamepad.vala
@@ -53,6 +53,10 @@ private class Games.RetroGamepad: Object, Retro.Controller {
                return (1 << Retro.ControllerType.JOYPAD) | (1 << Retro.ControllerType.ANALOG);
        }
 
+       public bool set_rumble_state (Retro.RumbleEffect effect, uint16 strength) {
+               return false;
+       }
+
        private bool get_button_pressed (Retro.JoypadId button) {
                switch (button) {
                case Retro.JoypadId.B: