audqt: Avoid overly large infopopup. Closes: #1435

With Qt 6 on Linux the popup is way too large when it is shown/moved
on a secondary monitor, even if it uses the same resolution as the
primary one. Qt 5 is not affected for some reason. Calling adjustSize()
fixes this for Qt 6 and does no harm on Qt 5.

src/libaudqt/util-qt.cc

@@ -103,6 +103,7 @@ void PopupWidget::showEvent(QShowEvent *)
         y += 3;
 
     move(x, y);
+    adjustSize();
 }
 
 void show_copy_context_menu(QWidget * parent, const QPoint & global_pos,