Xcode 11.3.1 is the latest supported version for macOS 10.14
It seems that in macOS 10.14 xip-package can't be expanded
through mount. It need to be fetched first.
Pick-to: 6.0
Pick-to: 6.1
Change-Id: I8c53787a2edde6b50abc7ec099ecc10b7515df2e
Reviewed-by: Qt CI Bot <qt_ci_bot@qt-project.org>
Reviewed-by: Tony Sarajärvi <tony.sarajarvi@qt.io>