sanjuuni: fix build with FFmpeg 7

Sanjuuni fails with FFmpeg 7:
```
configure: error: Could not find
libswresample library.
```
(per https://hydra.nixos.org/build/274775547)

libswresample is part of FFmpeg.

Upstream recommends this fix (we
apply a similar one):
MCJack123/sanjuuni#22 (comment)

Breakage introduced in:
#337855

Author: tomodachi94

pkgs/by-name/sa/sanjuuni/package.nix

@@ -31,6 +31,12 @@ stdenv.mkDerivation rec {
     opencl-clhpp
   ];
 
+  postPatch = ''
+    # TODO: Remove when https://github.com/MCJack123/sanjuuni/commit/778644b164c8877e56f9f5512480dde857133815 is released
+    substituteInPlace configure \
+      --replace-fail "swr_alloc_set_opts" "swr_alloc_set_opts2"
+  '';
+
   installPhase = ''
     runHook preInstall