[retro-gtk] input: Add missing MouseId values

[Bastien Nocera <hadess src gnome org>]

commit 4409d8c7c5c533ed1a04288232727a667ee1aaf4
Author: Bastien Nocera <hadess hadess net>
Date:   Thu Feb 16 08:38:51 2017 +0100

    input: Add missing MouseId values
    
    Horizontal wheel reporting was added since libretro.h was last updated.

 retro-gtk/input/device.vala |    4 +++-
 1 files changed, 3 insertions(+), 1 deletions(-)
---
diff --git a/retro-gtk/input/device.vala b/retro-gtk/input/device.vala
index a8ba783..74fccf5 100644
--- a/retro-gtk/input/device.vala
+++ b/retro-gtk/input/device.vala
@@ -164,7 +164,9 @@ public enum MouseId {
        RIGHT,
        WHEELUP,
        WHEELDOWN,
-       MIDDLE
+       MIDDLE,
+       HORIZ_WHEELUP,
+       HORIZ_WHEELDOWN,
 }
 
 /**