kdeApps.kmix: remove Qt 4 dependencies

pkgs/applications/kde-apps-14.12/default.nix

···
 #  make a copy of this directory first. After copying, be sure to delete ./tmp
 #  if it exists. Then follow the minor update instructions.
 
-{ autonix, kde4, kf55, pkgs, qt4, stdenv, debug ? false }:
+{ autonix, kde4, kf5, pkgs, qt4, stdenv, debug ? false }:
 
 with stdenv.lib; with autonix;
 
+let kf5Orig = kf5; in
+
 let
 
-  kf5 = kf55.override { inherit debug; };
+  kf5 = kf5Orig.override { inherit debug; };
 
   mirror = "mirror://kde";
 
···
       }
     );
 
+  qt5Only = tgt:
+    let qt4Deps = [ "KDE4" "Phonon" ];
+    in mapAttrs (name: if name == tgt then removePkgDeps qt4Deps else id);
+
   preResolve = super:
     fold (f: x: f x) super
       [
+        (qt5Only "kmix")
         (userEnvPkg "SharedMimeInfo")
         (userEnvPkg "SharedDesktopOntologies")
         (blacklist ["artikulate"]) # build failure, wrong boost?

pkgs/build-support/autonix/default.nix

···
   inherit generateCollection;
   inherit isDepAttr;
   inherit manifest;
+  inherit removePkgDeps;
   inherit resolveDeps;
   inherit userEnvPkg;
   inherit writeManifestXML;

pkgs/top-level/all-packages.nix

···
   };
 
   kdeApps_14_12 = recurseIntoAttrs (callPackage ../applications/kde-apps-14.12 {
+    kf5 = kf55;
     stdenv = overrideGCC stdenv gccStdInc;
   });
   kdeApps_latest = kdeApps_14_12;