Fix Haskell unittests without RAPI

Since we don't test for now the RAPI backend directly, we can simply
skip the import. Later we can make a conditional import if needed.

Signed-off-by: Iustin Pop <iustin@google.com>
Reviewed-by: Michael Hanselmann <hansmi@google.com>

htools/Ganeti/HTools/QC.hs

@@ -58,7 +58,6 @@ import qualified Ganeti.HTools.Luxi
 import qualified Ganeti.HTools.Node as Node
 import qualified Ganeti.HTools.Group as Group
 import qualified Ganeti.HTools.PeerMap as PeerMap
-import qualified Ganeti.HTools.Rapi
 import qualified Ganeti.HTools.Simu
 import qualified Ganeti.HTools.Text as Text
 import qualified Ganeti.HTools.Types as Types