The Abseil version of `StatusOr` does not come with the status macros
or the `Consume*` family of functions.
This change modifies the existing code to use the common denominator
of the API that is available between Abseil's own implementation of
`StatusOr` and the one from Tensorflow that we are currently using.
Change-Id: I5c37f68636a1fd54d153f95d7303ab8644abb774