Oops, the actual 'printf' for missing objects was missing.

Oops, the actual 'printf' for missing objects was missing.

Which made fsck very quiet about objects it hadn't found. So add
it.

We'll need to make things like these optional, because it's
perfectly ok to have partial history if you don't want it,
and don't want to go backwards. But for development, it's best
to always complain about missing sha1 object files that are
referenced from somewhere else.