EINTEGRITY was previously documented as a UFS-specific error for
mount(2). This documents EINTEGRITY as a filesystem-independent error
that may be reported by the backing store of a filesystem.
While here, document EIO as a filesystem-independent error for both
mount(2) and posix_fadvise(2). EIO was previously only documented
for UFS for mount(2).
Suggested by: mckusick