Qt4: include <vlc_aout.h> as needed

modules/gui/qt4/input_manager.cpp

@@ -33,6 +33,7 @@
 #include <vlc_keys.h>
 #include <vlc_url.h>
 #include <vlc_strings.h>
+#include <vlc_aout.h>
 
 #include <QApplication>
 

modules/gui/qt4/menus.cpp

@@ -37,6 +37,7 @@
 #include <vlc_common.h>
 #include <vlc_intf_strings.h>
 #include <vlc_vout.h>              /* vout_thread_t */
+#include <vlc_aout.h>
 
 #include "menus.hpp"
 

modules/gui/qt4/qt4.hpp

@@ -32,7 +32,6 @@
 #include <vlc_common.h>    /* VLC_COMMON_MEMBERS for vlc_interface.h */
 #include <vlc_interface.h> /* intf_thread_t */
 #include <vlc_playlist.h>  /* playlist_t */
-#include <vlc_aout.h>      /* AOUT_VOLUME_ */
 
 #define QT_NO_CAST_TO_ASCII
 #include <QString>