I falsely assumed that enum values would be generated automatically,
but now realize that the previous values I added were actually generated
from preprocessor define statements.

This change adds some missing values I intended to add in CL 59050.

Fixes golang/go#21623.

Change-Id: I3c40c8454ee1d323e1e4e014febe0874e859a378
Reviewed-on: https://go-review.googlesource.com/59090
Run-TryBot: Matt Layher <mdlayher@gmail.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Ian Lance Taylor <iant@golang.org>