Add smoke test for Bazel.

Test: Manually typed the commands in AOSP root.
Change-Id: I5ecf85f9d715f2759d27de4ac18b4928eb306550
diff --git a/build_test.bash b/build_test.bash
index ee979e7..a53a585 100755
--- a/build_test.bash
+++ b/build_test.bash
@@ -43,5 +43,16 @@
     ;;
 esac
 
+function bazel_cleanup {
+  "${TOP}/tools/bazel" shutdown
+}
+trap bazel_cleanup EXIT
+
+echo
+echo "Running Bazel smoke test..."
+"${TOP}/tools/bazel" info
+
+echo
+echo "Running Soong test..."
 soong_build_go multiproduct_kati android/soong/cmd/multiproduct_kati
 exec "$(getoutdir)/multiproduct_kati" "$@"