cad/pcb-rnd: update 3.1.1 → 3.1.6

• Enable testing, though marked TESTING_UNSAFE= yes for "ld: error: unable to find library -lrnd-3rd"
• Fix MASTER_SITES
• Some linting
• Sort LIB_DEPENDS
• Fix post-{patch,install} order

News:
http://www.repo.hu/projects/pcb-rnd/news.html

Release notes:
http://www.repo.hu/projects/pcb-rnd/releases/relnotes-3.1.2.txt
http://www.repo.hu/projects/pcb-rnd/releases/relnotes-3.1.3.txt
http://www.repo.hu/projects/pcb-rnd/releases/relnotes-3.1.4.txt
http://www.repo.hu/projects/pcb-rnd/releases/relnotes-3.1.5.txt
http://www.repo.hu/projects/pcb-rnd/releases/relnotes-3.1.6.txt

Changelogs:
http://www.repo.hu/projects/pcb-rnd/releases/changelog-3.1.6.txt

PR: 284174
Approved by: hasdalcodes@gmail.com (maintainer, timeout > 2 weeks)