libunwind on arm

[Manuel Bouyer <bouyer%antioche.eu.org@localhost>]

Hello,
it seems that we have our own implementation of libunwind in
src/sys/lib/libunwind/
Has it been tested on arm (earmv7hf if that matters) ?
I'm trying to get stack trace working in gperftools; it works on
x86_64 but not earmv7hf. Some comments in the commit log could suggest
that there are missing bits for earm ?

-- 
Manuel Bouyer <bouyer%antioche.eu.org@localhost>
     NetBSD: 26 ans d'experience feront toujours la difference
--