Fixes the following security issue:
CVE-2018-6789: Meh Chang discovered a buffer overflow flaw in a utility
function used in the SMTP listener of Exim, a mail transport agent. A
remote attacker can take advantage of this flaw to cause a denial of
service, or potentially the execution of arbitrary code via a specially
crafted message.
Dropped ChangeLog hunk and adjusted file path of upstream commit so it
applies to tarball.
Signed-off-by: Peter Korsgaard <peter@korsgaard.com>
