utils: Fix movefile() exception handling with python3

* with python3 this fails with:
  File: 'bitbake/lib/bb/utils.py', lineno: 799, function: movefile
       0795:        try:
       0796:            os.rename(src, destpath)
       0797:            renamefailed = 0
       0798:        except Exception as e:
   *** 0799:            if e[0] != errno.EXDEV:
       0800:                # Some random error.
       0801:                print("movefile: Failed to move", src, "to", dest, e)
       0802:                return None
       0803:            # Invalid cross-device-link 'bind' mounted or actually Cross-Device
  Exception: TypeError: 'OSError' object is not subscriptable

Signed-off-by: Martin Jansa <Martin.Jansa@gmail.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>