e2fsck: fix buffer overrun in revoke block scanning

Check the value of r_count to ensure that we never try to read revoke
records past the end of the revoke block.  It turns out that the
journal writing code in debugfs was also playing fast and loose with
the r_count, so fix that as well.

The Coverity bug was 1297508.

Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
7 files changed