Cocoa: Don't consume events when closing tool tips

With change acebf677 we treat Qt::ToolTip similar
to Qt::Popup and close them on a mouse click on the
parent window. This mouse click is not forwarded
to the standard mouse event handler.

Add an exception for Qt::ToolTip.

Task-number: QTBUG-38267
Change-Id: Ie3121f651a6ccc2427040e61db4f63967467604d
Reviewed-by: Eike Ziller <eike.ziller@digia.com>
Reviewed-by: Gabriel de Dietrich <gabriel.dedietrich@digia.com>