wireguard: Enable tools on other platforms

Wireguard is now split into two pretty much independent packages:
`wireguard` (Linux-specific kernel module) and `wireguard-tools`,
which is cross-platform.

pkgs/os-specific/linux/wireguard/default.nix

@@ -1,11 +1,10 @@
-{ stdenv, fetchurl, libmnl, kernel ? null }:
+{ stdenv, fetchurl, kernel }:
 
 # module requires Linux >= 3.10 https://www.wireguard.io/install/#kernel-requirements
-assert kernel != null -> stdenv.lib.versionAtLeast kernel.version "3.10";
+assert stdenv.lib.versionAtLeast kernel.version "3.10";
 
-let
+stdenv.mkDerivation rec {
   name = "wireguard-${version}";
-
   version = "0.0.20180514";
 
   src = fetchurl {
@@ -13,61 +12,28 @@ let
     sha256 = "1nk6yj1gdmpar99zzw39n1v795m6fxsrilg37d02jm780rgbd5g8";
   };
 
+  preConfigure = ''
+    cd src
+    sed -i '/depmod/,+1d' Makefile
+  '';
+
+  hardeningDisable = [ "pic" ];
+
+  KERNELDIR = "${kernel.dev}/lib/modules/${kernel.modDirVersion}/build";
+  INSTALL_MOD_PATH = "\${out}";
+
+  NIX_CFLAGS = ["-Wno-error=cpp"];
+
+  nativeBuildInputs = kernel.moduleBuildDependencies;
+
+  buildPhase = "make module";
+
   meta = with stdenv.lib; {
     homepage     = https://www.wireguard.com/;
     downloadPage = https://git.zx2c4.com/WireGuard/refs/;
-    description  = "A prerelease of an experimental VPN tunnel which is not to be depended upon for security";
+    description  = " Tools for the WireGuard secure network tunnel";
     maintainers  = with maintainers; [ ericsagnes mic92 zx2c4 ];
     license      = licenses.gpl2;
     platforms    = platforms.linux;
   };
-
-  module = stdenv.mkDerivation {
-    inherit src meta name;
-
-    preConfigure = ''
-      cd src
-      sed -i '/depmod/,+1d' Makefile
-    '';
-
-    hardeningDisable = [ "pic" ];
-
-    KERNELDIR = "${kernel.dev}/lib/modules/${kernel.modDirVersion}/build";
-    INSTALL_MOD_PATH = "\${out}";
-
-    NIX_CFLAGS = ["-Wno-error=cpp"];
-
-    nativeBuildInputs = kernel.moduleBuildDependencies;
-
-    buildPhase = "make module";
-  };
-
-  tools = stdenv.mkDerivation {
-    inherit src meta name;
-
-    preConfigure = "cd src";
-
-    buildInputs = [ libmnl ];
-
-    enableParallelBuilding = true;
-
-    makeFlags = [
-      "WITH_BASHCOMPLETION=yes"
-      "WITH_WGQUICK=yes"
-      "WITH_SYSTEMDUNITS=yes"
-      "DESTDIR=$(out)"
-      "PREFIX=/"
-      "-C" "tools"
-    ];
-
-    buildPhase = "make tools";
-
-    postInstall = ''
-      substituteInPlace $out/lib/systemd/system/wg-quick@.service \
-        --replace /usr/bin $out/bin
-    '';
-  };
-
-in if kernel == null
-   then tools
-   else module
+}