Vendor dependencies

Let's see how I like this workflow.

vendor/cxx/tools/buck/prelude/local_only.bzl

@@ -0,0 +1,30 @@
+# Copyright (c) Meta Platforms, Inc. and affiliates.
+#
+# This source code is licensed under both the MIT license found in the
+# LICENSE-MIT file in the root directory of this source tree and the Apache
+# License, Version 2.0 found in the LICENSE-APACHE file in the root directory
+# of this source tree.
+
+load("@prelude//cxx:cxx_context.bzl", "get_cxx_toolchain_info")
+load("@prelude//utils:utils.bzl", "value_or")
+
+def _is_core_tool(ctx: "context"):
+    return "is_core_tool" in ctx.attrs.labels
+
+def link_cxx_binary_locally(ctx: "context", cxx_toolchain: ["CxxToolchainInfo", None] = None) -> bool.type:
+    # core tools are linked on RE because they are a) small enough to do so and
+    # b) don't get build stamping so they do cache correctly.
+    if _is_core_tool(ctx):
+        return False
+    if not cxx_toolchain:
+        cxx_toolchain = get_cxx_toolchain_info(ctx)
+    link_locally = cxx_toolchain.linker_info.link_binaries_locally
+    if hasattr(ctx.attrs, "_link_binaries_locally_override"):
+        return value_or(ctx.attrs._link_binaries_locally_override, link_locally)
+    return link_locally
+
+def package_python_locally(ctx: "context", python_toolchain: "PythonToolchainInfo") -> bool.type:
+    if _is_core_tool(ctx) or getattr(ctx.attrs, "_package_remotely", False):
+        return False
+
+    return python_toolchain.build_standalone_binaries_locally