QEventDispatcher on macOS

Implementation of QAbstractEventDispatcher for macOS.

Used in Qt Core on macOS.

The sources can be found in qt5/qtbase/src/corelib/kernel/qeventdispatcher_cf_p.h.

 Copyright (c) 2007-2008, Apple, Inc.

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 Copyright (c) 2007-2008, Apple, Inc.

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