macosx: Don't re-center extensions on every dialog update

If the user has moved the extension dialog, we don't want to re-center it on every single update -- many extensions update their dialogs on every input change, and this behavior can cause the extension dialog to keep re-overlapping with the video, which is very frustrating.
Signed-off-by: Felix Paul Kühne <fkuehne@videolan.org>
(cherry picked from commit ad765c21ffe71fe27b3b6a03ebaa878408ba40ee)

Conflicts:
	modules/gui/macosx/ExtensionsDialogProvider.m

modules/gui/macosx/ExtensionsDialogProvider.m

@@ -561,17 +561,11 @@ static ExtensionsDialogProvider *_o_sharedInstance = nil;
 
         BOOL visible = !p_dialog->b_hide;
         if (visible)
-        {
-            [dialogWindow center];
             [dialogWindow makeKeyAndOrderFront:self];
-        }
         else
-        {
             [dialogWindow orderOut:nil];
-        }
     }
-    else if( p_dialog->b_kill )
-    {
+    else if( p_dialog->b_kill ) {
         [self destroyExtensionDialog:p_dialog];
     }
     vlc_cond_signal( &p_dialog->cond );