perl: update our copy of Mail::Address

perl: update our copy of Mail::Address

Update our copy of Mail::Address from 2.19 (Aug 22, 2017) to 2.20 (Jan
23, 2018). Like the preceding Error.pm update this is done simply to
keep up-to-date with upstream, and as can be shown from the diff
there's no functional changes.

The updated source was retrieved from
https://fastapi.metacpan.org/source/MARKOV/MailTools-2.20/lib/Mail/Address.pm

Signed-off-by: Ævar Arnfjörð Bjarmason <avarab@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>