Assert against use of unitialized variable

(cherry picked from commit 4a7cf6a7)

modules/gui/qt4/dialogs/sout.cpp

@@ -34,6 +34,7 @@
 #include <QString>
 #include <QFileDialog>
 #include <QToolButton>
+#include <assert.h>
 
 SoutDialog::SoutDialog( QWidget *parent, intf_thread_t *_p_intf, const QString& inputMRL )
            : QVLCDialog( parent,  _p_intf )
@@ -182,6 +183,9 @@ void SoutDialog::addDest( )
                 index = ui.destTab->addTab( idb, "Icecast" );
                 CONNECT( idb, mrlUpdated(), this, updateMRL() );
             }
+            break;
+        default:
+            assert(0);
     }
 
     ui.destTab->setCurrentIndex( index );