math/yices: Update 2.6.5 => 2.7.0, mark as PIE_UNSAFE
Changelogs:
- https://yices.csl.sri.com/release-notes.html
- https://github.com/SRI-CSL/yices2/compare/Yices-2.6.5...yices-2.7.0
- Switch MASTER_SITES to Github as upstream official site doesn't
contain tarball for 2.7.0
- Add second WWW for source code repository
- Correct LICENSE and LICENSE_FILE
- Have test issue closed https://github.com/SRI-CSL/yices2/issues/523
- Mark as PIE_UNSAFE
Approved by: yuri@ (maintainer, Mentor)
Differential Revision: https://reviews.freebsd.org/D52658