Include required files directly instead of pollution via ufs/ufsmount.h.

Sponsored by:	Nginx, Inc.


git-svn-id: svn+ssh://svn.freebsd.org/base/head@274906 ccf9f872-aa2e-dd11-9fc8-001c23d0bc1f
buf.h is not needed here, and pollutes when ufsmount.h is included
from userland code.

Sponsored by:	Nginx, Inc.


git-svn-id: svn+ssh://svn.freebsd.org/base/head@274907 ccf9f872-aa2e-dd11-9fc8-001c23d0bc1f