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.

nixos/modules/config/no-x-libs.nix

@@ -32,7 +32,6 @@ with lib;
       networkmanager-l2tp = pkgs.networkmanager-l2tp.override { withGnome = false; };
       networkmanager-openconnect = pkgs.networkmanager-openconnect.override { withGnome = false; };
       networkmanager-openvpn = pkgs.networkmanager-openvpn.override { withGnome = false; };
-      networkmanager-pptp = pkgs.networkmanager-pptp.override { withGnome = false; };
       networkmanager-vpnc = pkgs.networkmanager-vpnc.override { withGnome = false; };
       networkmanager-iodine = pkgs.networkmanager-iodine.override { withGnome = false; };
       pinentry = pkgs.pinentry_ncurses;

nixos/modules/services/networking/networkmanager.nix

@@ -135,8 +135,7 @@ in {
         default = { inherit networkmanager modemmanager wpa_supplicant
                             networkmanager-openvpn networkmanager-vpnc
                             networkmanager-openconnect networkmanager-fortisslvpn
-                            networkmanager-pptp networkmanager-l2tp
-                            networkmanager-iodine; };
+                            networkmanager-l2tp networkmanager-iodine; };
         internal = true;
       };
 
@@ -267,8 +266,6 @@ in {
       message = "You can not use networking.networkmanager with networking.wireless";
     }];
 
-    boot.kernelModules = [ "ppp_mppe" ]; # Needed for most (all?) PPTP VPN connections.
-
     environment.etc = with cfg.basePackages; [
       { source = configFile;
         target = "NetworkManager/NetworkManager.conf";
@@ -285,9 +282,6 @@ in {
       { source = "${networkmanager-fortisslvpn}/etc/NetworkManager/VPN/nm-fortisslvpn-service.name";
         target = "NetworkManager/VPN/nm-fortisslvpn-service.name";
       }
-      { source = "${networkmanager-pptp}/etc/NetworkManager/VPN/nm-pptp-service.name";
-        target = "NetworkManager/VPN/nm-pptp-service.name";
-      }
       { source = "${networkmanager-l2tp}/etc/NetworkManager/VPN/nm-l2tp-service.name";
         target = "NetworkManager/VPN/nm-l2tp-service.name";
       }

nixos/modules/services/x11/desktop-managers/gnome3.nix

@@ -182,8 +182,7 @@ in {
       { inherit (pkgs) networkmanager modemmanager wpa_supplicant;
         inherit (pkgs.gnome3) networkmanager-openvpn networkmanager-vpnc
                               networkmanager-openconnect networkmanager-fortisslvpn
-                              networkmanager-pptp networkmanager-iodine
-                              networkmanager-l2tp; };
+                              networkmanager-iodine networkmanager-l2tp; };
 
     # Needed for themes and backgrounds
     environment.pathsToLink = [ "/share" ];