By Veo Zhang via NetBSD
Tested it builds as an individual component (not as part of build world) but
haven't performed any tests on a file system.
You need to find someone more knowledgeable in that area (i.e. src-committer) to look over that change. Maybe someone who recently made some change to the same code area: https://svnweb.freebsd.org/base/head/sbin/fsck_msdosfs/