thc-ipv6: fix gcc-15 build

Without the chnage the build fails on `master` as
https://hydra.nixos.org/build/320117087:

    thc-ipv6-lib.c: In function 'thc_pcap_function':
    thc-ipv6-lib.c:127:36: error: too many arguments to function 'thc_open_ipv6'; expected 0, have 1
      127 |   if (thc_socket < 0) thc_socket = thc_open_ipv6(interface);
          |                                    ^~~~~~~~~~~~~ ~~~~~~~~~
    In file included from thc-ipv6-lib.c:75:
    thc-ipv6.h:211:23: note: declared here
      211 | extern int            thc_open_ipv6();
          |                       ^~~~~~~~~~~~~

pkgs/by-name/th/thc-ipv6/package.nix

@@ -2,6 +2,7 @@
   lib,
   stdenv,
   fetchFromGitHub,
+  fetchpatch,
   libpcap,
   openssl,
   libnetfilter_queue,
@@ -18,6 +19,16 @@ stdenv.mkDerivation rec {
     sha256 = "07kwika1zdq62s5p5z94xznm77dxjxdg8k0hrg7wygz50151nzmx";
   };
 
+  patches = [
+    # Fix gcc-15 build failure:
+    #   https://github.com/vanhauser-thc/thc-ipv6/pull/53
+    (fetchpatch {
+      name = "gcc-15.patch";
+      url = "https://github.com/vanhauser-thc/thc-ipv6/commit/c9617d5638196bd88336225a6abdfd45c3df0bcf.patch";
+      hash = "sha256-4+LmRsDInzzNFHvj8WK+r1fKeoLggQW7yrahC1d6WCs=";
+    })
+  ];
+
   buildInputs = [
     libpcap
     openssl