fetch-nupkg/overrides: fix missing libc++ dependency in SkiaSharp

Some earlier 3.x versions still don't build because they depend on
libc.musl-x86_64.so.1.

Fixes: #370827
(cherry picked from commit f1c31d6c1d)

pkgs/build-support/dotnet/fetch-nupkg/overrides.nix

@@ -79,7 +79,10 @@
       lib.optionalAttrs stdenv.hostPlatform.isLinux {
         nativeBuildInputs = old.nativeBuildInputs or [ ] ++ [ autoPatchelfHook ];
 
-        buildInputs = old.buildInputs or [ ] ++ [ fontconfig ];
+        buildInputs =
+          old.buildInputs or [ ]
+          ++ [ fontconfig ]
+          ++ lib.optional (lib.versionAtLeast old.version "4") (lib.getLib stdenv.cc.cc);
 
         preInstall = old.preInstall or "" + ''
           cd runtimes