(emaste/freebsd:makefs-wip) fix bug with bread getting wrong offset and sectorsize

[guest-svmhdvn]

Summary

main NetBSD commit:

• don't abuse vp->fs to mean struct fs for ffs and struct msdos_opts

[ngie]

Have you run the makefs tests, in addition to fstyp and other tests that rely on makefs yet?

[guest-svmhdvn]

Ed and I were discussing how to proceed with these changes. Instead of this review, I will post reviews for each individual feature change in makefs so it will be easier to manage. I haven't run the other tests that depend on makefs yet, I will do that before posting the other reviews. Can I abandon this revision? I will post the other reviews soon.

[emaste]

@ngie one other issue that we haven't fully resolved is the canonical method for running the tests on the uninstalled binary in the objdir - i.e., I'd like to do something like:

% make -C usr.sbin/makefs
% make -C usr.sbin/makefs check