SDK: Add a Makefile to build the C++ stuff.

sdk_build/data/cpp/setup.sh

Index: sdk_build/data/cpp/setup.sh
diff --git a/fusl/ldso/BUILD.gn b/sdk_build/data/cpp/setup.sh
old mode 100644
new mode 100755
similarity index 50%
copy from fusl/ldso/BUILD.gn
copy to sdk_build/data/cpp/setup.sh
index c2f581f19a28b615fcba66215a16cc1e4df2dbce..47fdd197e26fd6ac66902230a5d02efdc08eea04
--- a/fusl/ldso/BUILD.gn
+++ b/sdk_build/data/cpp/setup.sh
@@ -1,14 +1,10 @@
+#!/bin/bash
 # Copyright 2016 The Chromium Authors. All rights reserved.
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 
-import("//fusl/fusl.gni")
+# Note: In the SDK, this script lives in mojo_sdk_setup.
+SCRIPT_DIR=$(dirname $0)
 
-fusl_source_set("ldso") {
-  configs = [ "//fusl:fusl_no_stack_protector_config" ]
-
-  sources = [
-    "dlstart.c",
-    "dynlink.c",
-  ]
-}
+${SCRIPT_DIR}/download_mojom_tool.sh
+${SCRIPT_DIR}/download_clang.sh