I've already turned away one attempt to remove this field.
As the comment above the struct says, many tools know the layout.
The field cannot simply be removed.

It was one thing to remove the fields name, but the TODO should
not have been added.

Change-Id: If40eacf0eb35835082055e129e2b88333a0731b9
Reviewed-on: https://go-review.googlesource.com/17741Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
Reviewed-by: Ian Lance Taylor <iant@golang.org>