Add missing proctree locking to fill_kinfo_proc consumers.

This fixes r270444.

Pointy hat:	mjg
Reported by:	many
MFC after:	1 week


git-svn-id: svn+ssh://svn.freebsd.org/base/head@270834 ccf9f872-aa2e-dd11-9fc8-001c23d0bc1f