desktop-files-utils: add setupHook to remove mimeinfo.cache

Post-Installation scripts are running `update-desktop-database -q`
creating these files which obviously results in a lot of collisions.

Much better solution than eventually noticing their existence and
removing them in postInstall.

pkgs/applications/misc/font-manager/default.nix

@@ -49,10 +49,6 @@ stdenv.mkDerivation rec {
     patchShebangs meson_post_install.py
   '';
 
-  postInstall = ''
-    rm $out/share/applications/mimeinfo.cache
-  '';
-
   meta = {
     homepage = https://fontmanager.github.io/;
     description = "Simple font management for GTK+ desktop environments";

pkgs/development/tools/profiling/sysprof/default.nix

@@ -46,10 +46,6 @@ in stdenv.mkDerivation rec {
     "-Dsystemdunitdir=lib/systemd/system"
   ];
 
-  postInstall = ''
-    rm $out/share/applications/mimeinfo.cache
-  '';
-
   passthru = {
     updateScript = gnome3.updateScript {
       packageName = pname;

pkgs/tools/misc/desktop-file-utils/default.nix

@@ -21,6 +21,8 @@ stdenv.mkDerivation rec {
   nativeBuildInputs = [ pkgconfig ];
   buildInputs = [ glib libintl ];
 
+  setupHook = ./setup-hook.sh;
+
   meta = {
     homepage = http://www.freedesktop.org/wiki/Software/desktop-file-utils;
     description = "Command line utilities for working with .desktop files";

pkgs/tools/misc/desktop-file-utils/setup-hook.sh

@@ -0,0 +1,6 @@
+# Remove mimeinfo cache
+mimeinfoPreFixupPhase() {
+    rm -f $out/share/applications/mimeinfo.cache
+}
+
+preFixupPhases="$preFixupPhases mimeinfoPreFixupPhase"