libsupport: add checks to prevent buffer overrun bugs in quota code

libsupport: add checks to prevent buffer overrun bugs in quota code

A maliciously corrupted file systems can trigger buffer overruns in
the quota code used by e2fsck.  To fix this, add sanity checks to the
quota header fields as well as to block number references in the quota
tree.

Addresses: CVE-2019-5094
Addresses: TALOS-2019-0887
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
(cherry picked from commit 8dbe7b475ec5e91ed767239f0e85880f416fc384)

Gbp-Pq: Name libsupport-add-checks-to-prevent-buffer-.patch