unrar-free: add setupHook

This adds a setupHook to unrar-free which is parallel to the one in
unrar. This enables the unpackPhase to automatically use unrar-free to
unpack RAR files.

pkgs/by-name/un/unrar-free/package.nix

@@ -21,6 +21,8 @@ stdenv.mkDerivation (finalAttrs: {
 
   buildInputs = [ libarchive ];
 
+  setupHook = ./setup-hook.sh;
+
   meta = {
     description = "Free utility to extract files from RAR archives";
     longDescription = ''

pkgs/by-name/un/unrar-free/setup-hook.sh

@@ -0,0 +1,5 @@
+unpackCmdHooks+=(_tryUnrarFree)
+_tryUnrarFree() {
+    if ! [[ "$curSrc" =~ \.rar$ ]]; then return 1; fi
+    unrar-free -x "$curSrc" >/dev/null
+}