Log message:
Fix shells/fish NetBSD version detection for libexecinfo.

Log message:
Import fish-1.23.1 as shells/fish, packaged for wip by Moritz Wilhelmy,
Adam Hoka and hugor.

fish is a user friendly command line shell for UNIX-like operating
systems, written mainly with interactive use in mind.  It differs
from other shells in that it only provides as few commands as
built-ins as possible and has a daemon which allows it to have
shared variables and command-line history between shell instances.
It also features feature-rich tab-completion and has command-line
syntax highlighting.