gui: remove macOS ProgressBar workaround

Author: fanquake

src/qt/guiutil.h

@@ -230,19 +230,7 @@ namespace GUIUtil
         void mouseReleaseEvent(QMouseEvent *event);
     };
 
-#if defined(Q_OS_MAC)
-    // workaround for Qt OSX Bug:
-    // https://bugreports.qt-project.org/browse/QTBUG-15631
-    // QProgressBar uses around 10% CPU even when app is in background
-    class ProgressBar : public ClickableProgressBar
-    {
-        bool event(QEvent *e) {
-            return (e->type() != QEvent::StyleAnimationUpdate) ? QProgressBar::event(e) : false;
-        }
-    };
-#else
     typedef ClickableProgressBar ProgressBar;
-#endif
 
 } // namespace GUIUtil