This removes the fixed enumeration of emulated functions in favor of a
dynamic map. This makes the code more compact and flexible. The main
benefit is that maintaining the list emulated functions is a lot simpler
now.

Change-Id: Ic9951a496b9f021c76ad5b4c3daccd89af5ac093
Reviewed-on: https://chromium-review.googlesource.com/239871Tested-by: Olli Etuaho <oetuaho@nvidia.com>
Reviewed-by: Jamie Madill <jmadill@chromium.org>
Reviewed-by: Nicolas Capens <capn@chromium.org>