Qt/vlm: == instead of =

(cherry picked from commit 923575b1)
Signed-off-by: Jean-Baptiste Kempf <jb@videolan.org>

modules/gui/qt4/dialogs/vlm.cpp

@@ -559,7 +559,7 @@ void VLMBroadcast::update()
 
 void VLMBroadcast::togglePlayPause()
 {
-    if( b_playing = true )
+    if( b_playing )
     {
         VLMWrapper::ControlBroadcast( name, ControlBroadcastPause );
         playButton->setIcon( QIcon( QPixmap( ":/pause_16px" ) ) );