Unbreak buildbot dx host tests

Adds junit-host to buildbot host targets.

Test: art/tools/buildbot-build.sh --host -j100 && dalvik/dx/tests/run-all-tests
Change-Id: I1dcd670bf9ceac8715c73cb28130c43614ad0a5b
diff --git a/tools/buildbot-build.sh b/tools/buildbot-build.sh
index e63e6f1..d404466 100755
--- a/tools/buildbot-build.sh
+++ b/tools/buildbot-build.sh
@@ -65,7 +65,7 @@
 
 if [[ $mode == "host" ]]; then
   make_command="make $j_arg $extra_args $showcommands build-art-host-tests $common_targets"
-  make_command+=" dx-tests"
+  make_command+=" dx-tests junit-host"
   mode_suffix="-host"
 elif [[ $mode == "target" ]]; then
   if [[ -z "${ANDROID_PRODUCT_OUT}" ]]; then