Fix formatting of vmstat (1) so that it looks cleaner on standard 80
column displays. In particular it wraps far less often.

Submitted by: Andy Kosela <akosela@andykosela.com>
PR:           191976


git-svn-id: svn+ssh://svn.freebsd.org/base/head@273575 ccf9f872-aa2e-dd11-9fc8-001c23d0bc1f