bug#24892: {s, }brk removed from FreeBSD 11.x and later, arm64 architecture

[Eli Zaretskii]

unblock 21966 by 24892
block 24655 by 24892
thanks

> From: Paul Eggert <eggert@cs.ucla.edu>
> Date: Fri, 18 Nov 2016 14:22:07 -0800
> Cc: freebsd-hackers@freebsd.org, Brooks Davis <brooks@freebsd.org>,
>       24892@debbugs.gnu.org, Ashish SHUKLA <ashish.is@lostca.se>
> 
> Ed Maste wrote:
> > arm64 support was first available in a release in FreeBSD 11.0, without 
> > sbrk, and sbrk never existed on the stable/11 branch.
> 
> Thanks, I didn't know that. So Emacs has never worked in this environment.

Since Emacs never worked on FreeBSD/arm64, we don't need to block the
release of 25.2 on this issue (although it would be nice to have it
resolved by 25.2).