anchor.diff:      "${boolNo mumbleOverlay}overlay"
       "no-qt4-legacy-compat"
     ] ++ optionals (config == "murmur") [
  -    "no-ice"
  +    "${boolNo (ice != null)}ice"
       "${boolNo (grpc != null)}grpc"
       "qssldiffiehellmanparameters"
     ];
  
positive.code: , boost
  , fixesproto
  , grpc
  , inputproto
  , jack2_lib
  , libcap
  
negative.code:     xproto
    ] ++ optionals (config == "murmur") [
      grpc
      ice
      libcap
    ];
  
  