networkmanager-pptp: remove package

Currently broken on NixOS due to hardcoded modprobe binary path (see
bug #30756 from Oct 2017), no activity on a proposed fix for months.
As the protocol is terribly broken anyways, let's better remove it
completely, and not talk about anymore ;-)

Closes #30756.

pkgs/tools/networking/network-manager/pptp.nix

@@ -1,43 +0,0 @@
-{ stdenv, fetchurl, networkmanager, pptp, ppp, intltool, pkgconfig
-, libsecret, withGnome ? true, gnome3 }:
-
-let
-  pname   = "NetworkManager-pptp";
-  version = "1.2.4";
-in stdenv.mkDerivation rec {
-  name    = "${pname}${if withGnome then "-gnome" else ""}-${version}";
-
-  src = fetchurl {
-    url    = "mirror://gnome/sources/${pname}/${stdenv.lib.versions.majorMinor version}/${pname}-${version}.tar.xz";
-    sha256 = "bd97ce768c34cce6d5b5d43681149a8300bec754397a3f46a0d8d0aea7030c5e";
-  };
-
-  buildInputs = [ networkmanager pptp ppp libsecret ]
-    ++ stdenv.lib.optionals withGnome [ gnome3.gtk gnome3.libgnome-keyring
-                                        gnome3.networkmanagerapplet ];
-
-  nativeBuildInputs = [ intltool pkgconfig ];
-
-  postPatch = ''
-    sed -i -e 's%"\(/usr/sbin\|/usr/pkg/sbin\|/usr/local/sbin\)/[^"]*",%%g' ./src/nm-pptp-service.c
-
-    substituteInPlace ./src/nm-pptp-service.c \
-      --replace /sbin/pptp ${pptp}/bin/pptp \
-      --replace /sbin/pppd ${ppp}/bin/pppd
-  '';
-
-  configureFlags =
-    if withGnome then "--with-gnome --with-gtkver=3" else "--without-gnome";
-
-  passthru = {
-    updateScript = gnome3.updateScript {
-      packageName = pname;
-      attrPath = "networkmanager-pptp";
-    };
-  };
-
-  meta = {
-    description = "PPtP plugin for NetworkManager";
-    inherit (networkmanager.meta) maintainers platforms;
-  };
-}