gpu_tm: Use vendor module for header includes

Change-Id: I1c20f58006a10866164f1f5c5e29e3c0746dedc8
diff --git a/gpu_tonemapper/Android.mk b/gpu_tonemapper/Android.mk
index 769d0ab..89bad79 100644
--- a/gpu_tonemapper/Android.mk
+++ b/gpu_tonemapper/Android.mk
@@ -4,6 +4,7 @@
 include $(CLEAR_VARS)
 LOCAL_COPY_HEADERS_TO     := $(common_header_export_path)
 LOCAL_COPY_HEADERS        := TonemapFactory.h Tonemapper.h
+LOCAL_VENDOR_MODULE       := true
 include $(BUILD_COPY_HEADERS)
 
 include $(CLEAR_VARS)