openconnect: update to version 7.06 and support openssl or gnutls

pkgs/tools/networking/openconnect.nix

···
-{ stdenv, fetchurl, pkgconfig, vpnc, openssl, libxml2, zlib } :
+{ stdenv, fetchurl, pkgconfig, vpnc, openssl ? null, gnutls ? null, libxml2, zlib } :
+
+let
+  xor = a: b: (a || b) && (!(a && b));
+in
+
+assert xor (openssl != null) (gnutls != null);
 
 stdenv.mkDerivation rec {
-  name = "openconnect-5.02";
+  name = "openconnect-7.06";
 
   src = fetchurl {
     urls = [
       "ftp://ftp.infradead.org/pub/openconnect/${name}.tar.gz"
     ];
-    sha256 = "1y7dn42gd3763sgwv2j72xy9hsikd6y9x142g84kwdbn0y0psgi4";
+    sha256 = "1wkhmgfxkdkhy2p9w9idrgipxmxij2z4f88flfk3fifwd19nkkzs";
   };
 
   preConfigure = ''
···
     "--without-openssl-version-check"
   ];
 
-  propagatedBuildInputs = [ vpnc openssl libxml2 zlib ];
+  buildInputs = [ pkgconfig ];
+  propagatedBuildInputs = [ vpnc openssl gnutls libxml2 zlib ];
 }

pkgs/top-level/all-packages.nix

···
 
   vpnc = callPackage ../tools/networking/vpnc { };
 
-  openconnect = callPackage ../tools/networking/openconnect.nix { };
+  openconnect = openconnect_openssl;
+
+  openconnect_openssl = callPackage ../tools/networking/openconnect.nix {
+    gnutls = null;
+  };
+
+  openconnect_gnutls = lowPrio (openconnect.override {
+    openssl = null;
+    gnutls = gnutls;
+  });
 
   vtun = callPackage ../tools/networking/vtun { };