libmediainfo: add musl patch (#141966)

pkgs/development/libraries/libmediainfo/default.nix

···
-{ lib, stdenv, fetchurl, autoreconfHook, pkg-config, libzen, zlib }:
+{ lib, stdenv, fetchurl, autoreconfHook, pkg-config, libzen, zlib, fetchpatch }:
 
 stdenv.mkDerivation rec {
   version = "21.09";
···
   nativeBuildInputs = [ autoreconfHook pkg-config ];
   buildInputs = [ libzen zlib ];
 
-  sourceRoot = "./MediaInfoLib/Project/GNU/Library/";
+  patches = [
+    # fixes pkgsMusl.libmediainfo build
+    (fetchpatch {
+      url = "https://git.alpinelinux.org/aports/plain/community/libmediainfo/fix-include-signal.patch?id=b8d666a3d33575c184308e1176f4de9e519af577";
+      sha256 = "sha256-b3HoIwy/hKSh8jUakwVJpnPmYw5KUwZXgLW7IPMY4/c=";
+    })
+  ];
+
+  postPatch = "cd Project/GNU/Library";
 
   configureFlags = [ "--enable-shared" ];