Unit tests: Compile only on 'eng' builds.

metrics_collector_tests, metricsd_tests.

Bug: 26967770
Change-Id: I6d7e8fb6d3d98ab747d922bfeef05aa344b2179c
diff --git a/Android.mk b/Android.mk
index e140c62..bb262b4 100644
--- a/Android.mk
+++ b/Android.mk
@@ -200,7 +200,7 @@
 LOCAL_SRC_FILES := $(metricsd_tests_sources) $(metricsd_common)
 LOCAL_STATIC_LIBRARIES := libBionicGtestMain libgmock metricsd_protos metricsd_binder_proxy
 ifdef BRILLO
-LOCAL_MODULE_TAGS := debug
+LOCAL_MODULE_TAGS := eng
 endif
 include $(BUILD_NATIVE_TEST)
 
@@ -218,7 +218,7 @@
 LOCAL_STATIC_LIBRARIES := libBionicGtestMain libgmock metricsd_binder_proxy \
   $(metrics_collector_static_libraries)
 ifdef BRILLO
-LOCAL_MODULE_TAGS := debug
+LOCAL_MODULE_TAGS := eng
 endif
 include $(BUILD_NATIVE_TEST)