fritzing: fix qmake4Hook build

pass phoenix.pro and return unpack logic which were removed in 0b88755

pkgs/applications/science/electronics/fritzing/default.nix

@@ -9,8 +9,18 @@ stdenv.mkDerivation rec {
     sha256 = "181qnknq1j5x075icpw2qk0sc4wcj9f2hym533vs936is0wxp2gk";
   };
 
+  unpackPhase = ''
+    tar xjf ${src}
+  '';
+
   buildInputs = [ qtbase qtsvg boost qmakeHook ];
 
+  qmakeFlags = [ "phoenix.pro" ];
+
+  preConfigure = ''
+    cd fritzing-${version}.source
+  '';
+  
   meta = {
     description = "An open source prototyping tool for Arduino-based projects";
     homepage = http://fritzing.org/;