.mailmap: update to my shorter email address

Following f916ab0ccc ("send-email: more meaningful Message-ID"),
my own email address is too long :x

While I could have an even shorter address by one character with
"yhbt.net", "80x24.org" is more representative of my
hacking-related pursuits.

Signed-off-by: Eric Wong <e@80x24.org>
Signed-off-by: Eric Wong <normalperson@yhbt.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

.mailmap

@@ -51,6 +51,7 @@ Dirk Süsserott <newsletter@dirk.my1.cc>
 Eric Blake <eblake@redhat.com> <ebb9@byu.net>
 Eric Hanchrow <eric.hanchrow@gmail.com> <offby1@blarg.net>
 Eric S. Raymond <esr@thyrsus.com>
+Eric Wong <e@80x24.org> <normalperson@yhbt.net>
 Erik Faye-Lund <kusmabite@gmail.com> <kusmabite@googlemail.com>
 Eyvind Bernhardsen <eyvind.bernhardsen@gmail.com> <eyvind-git@orakel.ntnu.no>
 Florian Achleitner <florian.achleitner.2.6.31@gmail.com> <florian.achleitner2.6.31@gmail.com>