Qt: Fix the bug where the volume was losing 1% at each start

The bug originates from an implicit conversion to int. This commit
explicitly convert the value to qreal then use qRound to take the nearest
integer.
Signed-off-by: Jean-Baptiste Kempf <jb@videolan.org>

modules/gui/qt4/components/controller_widget.cpp

@@ -111,8 +111,8 @@ SoundWidget::SoundWidget( QWidget *_parent, intf_thread_t * _p_intf,
         layout->addWidget( volumeSlider, 0, Qt::AlignBottom  );
 
     /* Set the volume from the config */
-    volumeSlider->setValue( ( config_GetInt( p_intf, "volume" ) ) *
-                              VOLUME_MAX / (AOUT_VOLUME_MAX/2) );
+    volumeSlider->setValue( qRound( ( (qreal)config_GetInt( p_intf, "volume" ) ) *
+                              VOLUME_MAX / (AOUT_VOLUME_MAX/2) ) );
 
     /* Force the update at build time in order to have a muted icon if needed */
     updateVolume( volumeSlider->value() );