mtbl_verify: Remove assertion in verify_file()
mtbl_verify: Remove assertion in verify_file()

We now perform sanity checking of the index block offset in mtbl_reader,
so we no longer need this assertion. (And anyway, mtbl_verify shouldn't
be generating assertions.)

farsightsec/mtbl,rep/mtbl,rep/mtbl,rep/mtbl,farsightsec/mtbl