Fix MacOS build with SDK 10.7, XCode 4.3 and above

A hardcoded path condition failed and thus the dependency CoreWLAN
was not added. This caused missing symbols.

This patch is not necessary for Qt5 as only SDKs 10.6+ are supported.

Task-number: QTBUG-24361
Change-Id: I273a2be8d2bd7c72e8d7a1eed7c3e62a380e237a
Reviewed-by: Oswald Buddenhagen <oswald.buddenhagen@digia.com>
Reviewed-by: Tor Arne Vestbø <tor.arne.vestbo@digia.com>