Export brillo unittest_utils in the libbrillo-test module.

This module contains simple classes that can be usefull when writting
unittests in other projects.

Bug: None
TEST=mmma external/libbrillo; Used it from update_engine_unittests.

Change-Id: I4b5e576854c1a98a73c3581065a6cc35926f5db0
2 files changed