bitbake: compat, event: use OrderedDict from py2.7 for the event handlers

bitbake: compat, event: use OrderedDict from py2.7 for the event handlers

This ensures that our event handlers get run in registration order, making the
behavior more deterministic. I pulled in the python2.7 OrderedDict to avoid
essentially reimplementing a version of it ourselves, figuring we can drop it
when we bump our required python version next.

(Bitbake rev: 44aa0b0537d3fbd1272015e7677948f84d8c0607)

Signed-off-by: Christopher Larson <chris_larson@mentor.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>