Everything except for amd64, amd64p32, and 386 currently defines and
uses an abort function. This CL makes these match. The next CL will
recognize the abort function to make this more useful.

Change-Id: I7c155871ea48919a9220417df0630005b444f488
Reviewed-on: https://go-review.googlesource.com/93660
Run-TryBot: Austin Clements <austin@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Keith Randall <khr@golang.org>