To add another data point, the latest master builds and runs well for me on NetBSD 7.0.1_PATCH amd64 (GCC (nb2 20150115) 4.8.4). I used it for a while with normal editing and packages like Magit, W3m, SLIME and etc. No problems so far.

On Sun, Dec 11, 2016 at 11:33 AM, Eli Zaretskii <eliz@gnu.org> wrote:

> From: Ken Raeburn <raeburn@raeburn.org>
> Date: Sat, 10 Dec 2016 21:51:13 -0500
> Cc: emacs-devel@gnu.org,
> Tom Tromey <tom@tromey.com>
>
> The branch builds & runs fine for me on Mac OS X 10.11.6 (i.e., one major release out of date). Only tested with a few hours of normal code editing work locally and via TRAMP so far though.

Thanks. You can go back to master, now that concurrency landed there.