plank: hide launcher in pantheon

pkgs/applications/misc/plank/default.nix

···
     "INTROSPECTION_TYPELIBDIR=$(out)/lib/girepository-1.0"
   ];
 
+  # Make plank's application launcher hidden in Pantheon
+  patches = [ ./hide-in-pantheon.patch ];
+
   postPatch = ''
     substituteInPlace ./configure \
       --replace "/usr/bin/file" "${file}/bin/file"

pkgs/applications/misc/plank/hide-in-pantheon.patch

···
+diff --git a/data/plank.desktop.in b/data/plank.desktop.in
+index 330c3a4..e1bdf5f 100644
+--- a/data/plank.desktop.in
++++ b/data/plank.desktop.in
+@@ -8,3 +8,4 @@ Exec=plank
+ Icon=plank
+ Terminal=false
+ NoDisplay=false
++NotShowIn=Pantheon;