stand: Nuke double-semicolons

A distinct number of double-semicolons have ended up in FreeBSD. Take a
pass at getting rid of many of these harmless typos.

Reviewed by: emaste, imp
Pull Request: https://github.com/freebsd/freebsd-src/pull/609
Differential Revision: https://reviews.freebsd.org/D31717

(cherry picked from commit 798ea06f07778f69297bcb9c88738d115bf0369e)