Make sballoc() and sbfree() functions. Ideally, they could be marked
as static, but unfortunately Infiniband (ab)uses them.

Sponsored by:	Nginx, Inc.


git-svn-id: svn+ssh://svn.freebsd.org/base/head@275312 ccf9f872-aa2e-dd11-9fc8-001c23d0bc1f