bitbake-layers: add copyright notice

This ought to have been added earlier. (I consulted with Chris Larson on
the notice covering his work.)

(Bitbake rev: 69ed02b645bdc28c1bf24e436beeed37d226b56b)

Signed-off-by: Paul Eggleton <paul.eggleton@linux.intel.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>

bitbake/bin/bitbake-layers

@@ -4,6 +4,9 @@
 # displaying useful information, or acting against them.
 # See the help output for details on available commands.
 
+# Copyright (C) 2011 Mentor Graphics Corporation
+# Copyright (C) 2012 Intel Corporation
+
 import cmd
 import logging
 import os