read_entry did not verify that current chunk has enough data left
for a minimal entry. Thus we could try to read an entry from the slack
left in a chunk, and get lost in the file (pos > next, skip very much
-> eof). And also give false errors about corruption.
Message-Id: <1452517700-599-1-git-send-email-calle@scylladb.com>
(cherry picked from commit 7f4985a017)