package/mutt: add security fixes from Ubuntu for CVE-2021-3181

package/mutt: add security fixes from Ubuntu for CVE-2021-3181

Fixes the following security issue:

- CVE-2021-3181: rfc822.c in Mutt through 2.0.4 allows remote attackers to
  cause a denial of service (mailbox unavailability) by sending email
  messages with sequences of semicolon characters in RFC822 address fields
  (aka terminators of empty groups).  A small email message from the
  attacker can cause large memory consumption, and the victim may then be
  unable to see email messages from other persons.

Signed-off-by: Peter Korsgaard <peter@korsgaard.com>