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
diff --git a/Android.mk b/Android.mk
index 59a9b9b..00190db 100644
--- a/Android.mk
+++ b/Android.mk
@@ -95,6 +95,7 @@
     brillo/http/http_transport_fake.cc \
     brillo/message_loops/fake_message_loop.cc \
     brillo/streams/fake_stream.cc \
+    brillo/unittest_utils.cc \
 
 libbrillo_test_sources := \
     brillo/asynchronous_signal_handler_unittest.cc \
diff --git a/libbrillo.gypi b/libbrillo.gypi
index 2b5027b..0a641ba 100644
--- a/libbrillo.gypi
+++ b/libbrillo.gypi
@@ -165,6 +165,7 @@
         'brillo/http/http_transport_fake.cc',
         'brillo/message_loops/fake_message_loop.cc',
         'brillo/streams/fake_stream.cc',
+        'brillo/unittest_utils.cc',
       ],
       'includes': ['../common-mk/deps.gypi'],
     },