[Qt] Option key combinations do not work in Input Elements.

https://bugs.webkit.org/show_bug.cgi?id=120423

Q_WS_MAC is obsolete. We should use Q_OS_MAC instead.
This caused QTBUG-32388.

* WebCoreSupport/EditorClientQt.cpp:
(WebCore::EditorClientQt::handleKeyboardEvent):

Change-Id: Id884a2da61066e59bf733a83fd47346c270f7b8d
Reviewed-by: Allan Sandfeld Jensen <allan.jensen@digia.com>
Reviewed-by: Pierre Rossi <pierre.rossi@gmail.com>