security/doas: Update to version 6.0p.
- Pull tarball from a GitHub release rather than a commit.
- Update license information. There is code under BSD2CLAUSE and code under ISCL.
PR: 217176
Submitted by: jsmith@resonatingmedia.com (maintainer)
Approved by: mat, swills (mentor, implicit)
Differential Revision: https://reviews.freebsd.org/D9664