efivar: mark as broken if hostPlatform.is32bit

pkgs/by-name/ef/efivar/package.nix

···
     homepage = "https://github.com/rhboot/efivar";
     platforms = platforms.linux;
     license = licenses.lgpl21Only;
+    # See https://github.com/NixOS/nixpkgs/issues/388309
+    broken = stdenv.hostPlatform.is32bit;
   };
 }