afuse: add darwin build

pkgs/os-specific/linux/afuse/default.nix

@@ -11,11 +11,18 @@ stdenv.mkDerivation {
   nativeBuildInputs = [ autoreconfHook pkg-config ];
   buildInputs = [ fuse ];
 
+  postPatch = lib.optionalString stdenv.isDarwin ''
+    # Fix the build on macOS with macFUSE installed
+    substituteInPlace configure.ac --replace \
+      'export PKG_CONFIG_PATH=/usr/local/lib/pkgconfig:$PKG_CONFIG_PATH' \
+      ""
+  '';
+
   meta = {
     description = "Automounter in userspace";
     homepage = "https://github.com/pcarrier/afuse";
     license = lib.licenses.gpl2;
     maintainers = [ lib.maintainers.marcweber ];
-    platforms = lib.platforms.linux;
+    platforms = lib.platforms.unix;
   };
 }