libhardware: add stub audio and audio_policy modules

Change-Id: Ib6c0c49dbc369b735b2ac5fb5b583de96c3e9f3e
Signed-off-by: Dima Zavin <dima@android.com>
diff --git a/modules/Android.mk b/modules/Android.mk
index a7278bb..04b9140 100644
--- a/modules/Android.mk
+++ b/modules/Android.mk
@@ -1,2 +1,2 @@
-hardware_modules := gralloc hwcomposer
+hardware_modules := gralloc hwcomposer audio
 include $(call all-named-subdir-makefiles,$(hardware_modules))