skin2: call interaction_Register()

The destructor called interaction_Unregister(), thus also call interaction_Register()
(cherry picked from commit af9d16c5)
Signed-off-by: Jean-Baptiste Kempf <jb@videolan.org>

modules/gui/skins2/src/vlcproc.cpp

@@ -190,6 +190,8 @@ VlcProc::VlcProc( intf_thread_t *pIntf ): SkinObject( pIntf ),
 
     // initialize variables refering to liblvc and playlist objects
     init_variables();
+
+    interaction_Register( pIntf );
 }