tomahawk: Qt 5 infrastructure upgrade

pkgs/applications/audio/tomahawk/default.nix

···
 assert enableKDE       -> kdelibs      != null;
 assert enableTelepathy -> telepathy_qt != null;
 
-let
-  quazipQt4 = quazip.override { qt = qt4; };
-in stdenv.mkDerivation rec {
+stdenv.mkDerivation rec {
   name = "tomahawk-${version}";
   version = "0.8.4";
 
···
 
   buildInputs = [
     cmake pkgconfig attica boost gnutls libechonest liblastfm lucenepp phonon
-    qca2 qjson qt4 qtkeychain quazipQt4 sparsehash taglib websocketpp
+    qca2 qjson qt4 qtkeychain quazip sparsehash taglib websocketpp
     makeWrapper
   ] ++ stdenv.lib.optional enableXMPP      libjreen
     ++ stdenv.lib.optional enableKDE       kdelibs

pkgs/top-level/all-packages.nix

···
     enableXMPP      = config.tomahawk.enableXMPP      or true;
     enableKDE       = config.tomahawk.enableKDE       or false;
     enableTelepathy = config.tomahawk.enableTelepathy or false;
+    quazip = qt5.quazip.override { qt = qt4; };
   };
 
   torchat = callPackage ../applications/networking/instant-messengers/torchat {