libbrillo: add support for "a(ubay)" D-Bus type

The "a(ubay)" D-Bus type is needed by shill to handle the Pco property
of the org.freedesktop.ModemManager1.Modem3gpp interface exposed by
ModemManager.

BUG=b:112664666
TEST=Run unit tests.

Change-Id: Ia4ca839c6c8b77ed552f379f9144dd4c8bfc2d11
Reviewed-on: https://chromium-review.googlesource.com/1181529
Commit-Ready: Ben Chan <benchan@chromium.org>
Tested-by: Ben Chan <benchan@chromium.org>
Reviewed-by: Dan Erat <derat@chromium.org>
Reviewed-by: Mike Frysinger <vapier@chromium.org>
2 files changed