darwin-frameworks: add hook for private frameworks to CoreMIDI

Some parts of CoreMIDI depend on private frameworks, this enables eg.
adding -framework MultitouchSupport to a build.

pkgs/os-specific/darwin/apple-sdk/default.nix

@@ -210,6 +210,13 @@ in rec {
       ];
     });
 
+    CoreMIDI = stdenv.lib.overrideDerivation super.CoreMIDI (drv: {
+      __propagatedImpureHostDeps = drv.__propagatedImpureHostDeps ++ [
+        "/System/Library/PrivateFrameworks/"
+      ];
+      setupHook = ./private-frameworks-setup-hook.sh;
+    });
+
     Security = stdenv.lib.overrideDerivation super.Security (drv: {
       setupHook = ./security-setup-hook.sh;
     });