security/p5-Unix-setuid: create port

This module is inspired by File::chdir and File::umask, using a tied
scalar variable to get/set stuffs. One benefit of this is being able to
use Perl's "local" with it, effectively setting something locally.

WWW: https://metacpan.org/release/Unix-setuid

PR: 235732
Submitted by: Zane C. Bowers-Hadley <vvelox@vvelox.net>