Improve largeobject regression test to show size of object read from file.

Improve largeobject regression test to show size of object read from file.

The idea here is to provide a more easily diagnosable failure diff when
the problem is that tenk.data has been DOS-ified, as I believe to be
happening currently on buildfarm member hamerkop.  Per suggestion from
Magnus Hagander.

Also, sync output/largeobject_1.source with current regression test.
Failure to do that in commit 3a0e4d36ebd7f477822d5bae41ba121a40d22ccc
turns out to be the real reason that hamerkop has been complaining.