update URL to the marc.info mail archive

The name marc.theaimsgroup.com is no longer active, and has
migrated to marc.info.

Signed-off-by: Ondřej Bílka <neleai@seznam.cz>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Git 1.8.3.4

Signed-off-by: Junio C Hamano <gitster@pobox.com>