the test uses CoreFoundation api directly, so it must link it
explicitly.
amends 6c8f32388b.
Change-Id: I76b7d8ab41d6a66138eb45bd0f067cfee8e96cb8
Reviewed-by: Tor Arne Vestbø <tor.arne.vestbo@qt.io>
Reviewed-by: Thiago Macieira <thiago.macieira@intel.com>