[fusl] Build libcxx atop fusl

fusl/tools/copy_libcxx_headers.py

Index: fusl/tools/copy_libcxx_headers.py
diff --git a/fusl/tools/copy_libcxx_headers.py b/fusl/tools/copy_libcxx_headers.py
new file mode 100644
index 0000000000000000000000000000000000000000..220c9190bdd5b865ab3eabdc2e4092af96e8bea2
--- /dev/null
+++ b/fusl/tools/copy_libcxx_headers.py
@@ -0,0 +1,34 @@
+# 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 os
+import shutil
+import sys
+
+
+def copytree(source_dir, target_dir):
+  """Copy a tree.
+
+  This is needed because shutil.copytree requires that |target| not
+  exist yet.
+
+  """
+
+  for file in os.listdir(source_dir):
+    source = os.path.join(source_dir, file)
+    target = os.path.join(target_dir, file)
+    if os.path.isfile(source):
+      shutil.copy(source, target)
+    else:
+      copytree(source, target)
+
+
+def main():
+  source_path = sys.argv[1]
+  target_path = sys.argv[2]
+  copytree(source_path, target_path)
+
+
+if __name__ == '__main__':
+  main()