Migrate Apple CROSSTOOL to starlark.

RELNOTES: None.
PiperOrigin-RevId: 231209609
diff --git a/tools/migration/BUILD b/tools/migration/BUILD
index fbc2ed1..0c9a749 100644
--- a/tools/migration/BUILD
+++ b/tools/migration/BUILD
@@ -113,3 +113,11 @@
         "@com_github_golang_protobuf//proto:go_default_library",
     ],
 )
+
+filegroup(
+    name = "bazel_osx_p4deps",
+    srcs = [
+        "BUILD",
+        "ctoolchain_compare.bzl",
+    ],
+)