gui/macosx: fixes equalizer issue #3718.

Signed-off-by: Jean-Baptiste Kempf <jb@videolan.org>
(cherry picked from commit 4a65401d)
Signed-off-by: Jean-Baptiste Kempf <jb@videolan.org>

modules/gui/macosx/equalizer.m

@@ -98,7 +98,7 @@ static void ChangeFiltersString( intf_thread_t *p_intf,
          }
     }
 
-    aout_EnableFilter( p_object, psz_string, false);
+    aout_EnableFilter( pl_Get( p_intf ), psz_string, b_add);
 
     if( (BOOL)config_GetInt( p_object, "macosx-eq-keep" ) == YES )
     {

modules/gui/macosx/extended.m

@@ -733,7 +733,7 @@ static VLCExtended *_o_sharedInstance = nil;
     }
     else
     {
-        aout_EnableFilter( p_aout, psz_string, false );
+        aout_EnableFilter( pl_Get( p_intf ), psz_string, b_add );
     }
     free( psz_string );