Convert telnet to standalone derivation

Using all of `inetutils` resulted in commands such as `ping` and `ping6` being replaced, which is not desirable.

pkgs/default.nix

@@ -1,5 +1,6 @@
 { pkgs, ... }: {
   ipsw = pkgs.callPackage ./ipsw.nix { };
   monaco-powerline = pkgs.callPackage ./monaco-powerline/default.nix { };
+  telnet = pkgs.callPackage ./telnet.nix { };
   swiftformat = pkgs.callPackage ./swiftformat.nix { };
 }

pkgs/telnet.nix

@@ -0,0 +1,21 @@
+{ pkgs, lib, stdenvNoCC }:
+
+stdenvNoCC.mkDerivation rec {
+  pname = "telnet";
+  version = pkgs.inetutils.version;
+
+  dontUnpack = true;
+
+  postBuild = ''
+    mkdir -p $out/bin
+    ln -sf "${pkgs.inetutils}/bin/telnet" $out/bin/telnet
+
+    mkdir -p $out/share/man/man1
+    ln -sf "${pkgs.inetutils}/share/man/man1" $out/share/man/man1
+  '';
+
+  meta = with lib; {
+    description = "telnet from inetutils as a standalone derivation";
+    platforms = pkgs.inetutils.meta.platforms;
+  };
+}