rdfind: autoreconf to fix build with gcc 16

the configure script in the tarball was generated with autoconf 2.72,
which tries to switch to c++11 and causes failing builds with gcc 16
(which defaults to c++20). an update to 1.8.0 does not fix this issue,
so we autoreconf using the version from Nixpkgs (presently autoconf
2.73).

pkgs/by-name/rd/rdfind/package.nix

@@ -2,6 +2,7 @@
   lib,
   stdenv,
   fetchurl,
+  autoreconfHook,
   nettle,
 }:
 
@@ -14,6 +15,11 @@ stdenv.mkDerivation (finalAttrs: {
     sha256 = "sha256-eMRjFS4dnk/Rv+uDuckt9ef8TF+Tx9Qm+x9++ivk3yk=";
   };
 
+  # the built-in configure script was generated by autoconf 2.72 and
+  # passes -std=gnu++11 when using gcc 16 instead of the intended c++20.
+  # autoconf 2.73 fixes this, so we autoreconf to avoid this issue.
+  nativeBuildInputs = [ autoreconfHook ];
+
   buildInputs = [ nettle ];
 
   meta = {