Add a snapshot of flutter/engine/src/build to our sdk

build/gn_run_binary.py

Index: build/gn_run_binary.py
diff --git a/build/gn_run_binary.py b/build/gn_run_binary.py
new file mode 100644
index 0000000000000000000000000000000000000000..7d83f6136fd70e05e0c3628b527a094f1b69a2b8
--- /dev/null
+++ b/build/gn_run_binary.py
@@ -0,0 +1,22 @@
+# Copyright 2014 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.
+
+"""Helper script for GN to run an arbitrary binary. See compiled_action.gni.
+
+Run with:
+  python gn_run_binary.py <binary_name> [args ...]
+"""
+
+import sys
+import subprocess
+
+# This script is designed to run binaries produced by the current build. We
+# always prefix it with "./" to avoid picking up system versions that might
+# also be on the path.
+path = './' + sys.argv[1]
+
+# The rest of the arguements are passed directly to the executable.
+args = [path] + sys.argv[2:]
+
+sys.exit(subprocess.call(args))