QTsound: only available on QTKit 7.6.3 and over

This doesn't solve the MacOS10.5.sdk issue yet, but is a necessary step
I wonder how Apple can ship such broken SDKs, anyway
(cherry picked from commit 62eac017)
Signed-off-by: Jean-Baptiste Kempf <jb@videolan.org>

modules/access/qtsound.m

@@ -39,6 +39,9 @@
 #include <vlc_demux.h>
 #include <vlc_dialog.h>
 
+//#define QTKIT_VERSION_MIN_REQUIRED 70603
+#define QTKIT_VERSION_MAX_ALLOWED 70700
+
 #import <QTKit/QTKit.h>
 
 /*****************************************************************************