MFC r256687:

Upgrade to the latest version of mtree from NetBSD.  This revision
re-removes the printing of size for non-regular files, supports
type-less root (.) entries as seen in a couple ports, and corrects a bug
in -N that caused expanded Subversion $FreeBSD$ strings in comments to
be processed as /etc/group entries.

Includes one trivial portability fix (including <stdint.h> in three
files) that has been committed upstream.

Approved by:	re (glebius)
MFC r256450:

  Rename libbsdyml to libyaml, make private, and bump
  SHLIB_MAJOR to 1.0

Approved by:	bapt
Approved by:	re (glebius)