fretboard: fix build on darwin

pkgs/by-name/fr/fretboard/package.nix

@@ -1,6 +1,7 @@
 { lib
 , blueprint-compiler
 , cargo
+, darwin
 , desktop-file-utils
 , fetchFromGitHub
 , glib
@@ -48,8 +49,14 @@ stdenv.mkDerivation rec {
     glib
     gtk4
     libadwaita
+  ] ++ lib.optionals stdenv.isDarwin [
+    darwin.apple_sdk.frameworks.Foundation
   ];
 
+  env.NIX_CFLAGS_COMPILE = toString (lib.optionals stdenv.cc.isClang [
+    "-Wno-error=incompatible-function-pointer-types"
+  ]);
+
   meta = with lib; {
     description = "Look up guitar chords";
     homepage = "https://github.com/bragefuglseth/fretboard";