When checking if a link exists before creating it, use os.path.lexists() as
otherwise os.path.exists() on a broken link will return False.
(From OE-Core rev: ec24b6de2b8686e1f779fef3a963e66f70eeba74)
Signed-off-by: Ross Burton <ross.burton@intel.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>