rtorrent: Add option to build with Lua support

(cherry picked from commit 2a6dc58319)

pkgs/by-name/rt/rtorrent/package.nix

@@ -14,6 +14,8 @@
   zlib,
   nixosTests,
   gitUpdater,
+  withLua ? false,
+  lua5_4_compat,
 }:
 
 stdenv.mkDerivation (finalAttrs: {
@@ -50,12 +52,14 @@ stdenv.mkDerivation (finalAttrs: {
     ncurses
     openssl
     zlib
-  ];
+  ]
+  ++ lib.optionals withLua [ lua5_4_compat ];
 
   configureFlags = [
     "--with-xmlrpc-tinyxml2"
     "--with-posix-fallocate"
-  ];
+  ]
+  ++ lib.optionals withLua [ "--with-lua" ];
 
   passthru = {
     updateScript = gitUpdater { rev-prefix = "v"; };