security/sha1collisiondetection: a tool to detect SHA-1 collisions

https://github.com/cr-marcstevens/sha1collisiondetection

PR: 217733
Submitted by: jharris@widomaker.com (maintainer)
Reviewed by: mat
Approved by: swills (mentor, implicit)
Differential Revision: https://reviews.freebsd.org/D9998