Regenerate ztypes for openbsd/arm - most of the changes relate to the OpenBSD armv7 port
switching to EABI in September 2016.

Also use signed char when generating openbsd/arm ztypes, to avoid inconsistencies between
architectures impacting MI code.

Change-Id: I9d2e19c1ac045922e270896861c830f94fc59c10
Reviewed-on: https://go-review.googlesource.com/c/153578
Run-TryBot: Ian Lance Taylor <iant@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Ian Lance Taylor <iant@golang.org>