Add the original copyright notice to _macos_libfile.py

Author: abravalheri

setuptools/command/_macosx_libfile.py

@@ -1,3 +1,10 @@
+# This file was originally contributed to the pypa/wheel project under
+# The following license and copyright notice:
+#
+# MIT License
+#
+# Copyright (c) 2012 Daniel Holth <[email protected]> and contributors
+
 """
 IMPORTANT: THIS FILE IS NOW IN "MAINTENANCE MODE".
 DO NOT IMPORT THIS MODULE DIRECTLY.