audio hal: explicitly import headers

Test: works with BOARD_VNDK_VERSION := current
Bug: 33241851
Change-Id: I34983a5527a16e8e9f5a6a87edac0b741aeb67d6
diff --git a/audio/effect/2.0/default/Android.mk b/audio/effect/2.0/default/Android.mk
index bbcf298..f89d4f7 100644
--- a/audio/effect/2.0/default/Android.mk
+++ b/audio/effect/2.0/default/Android.mk
@@ -36,4 +36,11 @@
     android.hardware.audio.effect@2.0 \
     android.hidl.memory@1.0 \
 
+LOCAL_HEADER_LIBRARIES := \
+    libaudio_system_headers \
+    libaudioclient_headers \
+    libeffects_headers \
+    libhardware_headers \
+    libmedia_headers \
+
 include $(BUILD_SHARED_LIBRARY)