romdirfs: add darwin build

pkgs/tools/filesystems/romdirfs/default.nix

···
     description = "FUSE for access Playstation 2 IOP IOPRP images and BIOS dumps";
     homepage = "https://github.com/mlafeldt/romdirfs";
     license = licenses.gpl3;
-    platforms = platforms.linux;
+    platforms = platforms.unix;
     maintainers = with maintainers; [ ];
   };
 }

pkgs/top-level/all-packages.nix

···
 
   rmount = callPackage ../tools/filesystems/rmount {};
 
-  romdirfs = callPackage ../tools/filesystems/romdirfs {};
+  romdirfs = callPackage ../tools/filesystems/romdirfs {
+    stdenv = gccStdenv;
+  };
 
   rss-glx = callPackage ../misc/screensavers/rss-glx { };