darwin.apple_sdk.frameworks.CoreSymbolication: expose under SDK 11.0

This is used by the `root` package, and otherwise prevents the
nixpkgs.tarball build from succeeding (e.g.
https://hydra.nixos.org/build/146838433).

pkgs/os-specific/darwin/apple-sdk-11.0/private-frameworks.nix

@@ -15,4 +15,7 @@
   SignpostMetrics = {};
   PassKitCore = {};
   SkyLight = {};
+
+  # Also expose CoreSymbolication; used by `root` package.
+  CoreSymbolication = {};
 }