libdvdnav{,_4_2_1}: move to pkgs/by-name

this shouldn't create any rebuilds

pkgs/by-name/li/libdvdnav_4_2_1/package.nix

@@ -3,9 +3,11 @@
   stdenv,
   fetchurl,
   pkg-config,
-  libdvdread,
+  libdvdread_4_9_9,
 }:
-
+let
+  libdvdread = libdvdread_4_9_9;
+in
 stdenv.mkDerivation rec {
   pname = "libdvdnav";
   version = "4.2.1";

pkgs/top-level/all-packages.nix

@@ -7143,11 +7143,6 @@ with pkgs;
   libdbusmenu-gtk2 = libdbusmenu.override { gtkVersion = "2"; };
   libdbusmenu-gtk3 = libdbusmenu.override { gtkVersion = "3"; };
 
-  libdvdnav = callPackage ../development/libraries/libdvdnav { };
-  libdvdnav_4_2_1 = callPackage ../development/libraries/libdvdnav/4.2.1.nix {
-    libdvdread = libdvdread_4_9_9;
-  };
-
   libdvdread = callPackage ../development/libraries/libdvdread { };
   libdvdread_4_9_9 = callPackage ../development/libraries/libdvdread/4.9.9.nix { };