Fix use of local-generated-sources-dir.

For a host module, you need to specify LOCAL_IS_HOST_MODULE (as well as
LOCAL_MODULE and LOCAL_MODULE_CLASS) before
$(call local-generated-sources-dir).

Bug: 26239768
Change-Id: Ia164f8d0b99b64e21dc3f96fe55e34f2bdb33d23
diff --git a/Android.mk b/Android.mk
index c9a2297..8e4aa9f 100644
--- a/Android.mk
+++ b/Android.mk
@@ -85,6 +85,7 @@
 include $(CLEAR_VARS)
 LOCAL_MODULE := update_metadata-protos
 LOCAL_MODULE_CLASS := STATIC_LIBRARIES
+LOCAL_IS_HOST_MODULE := true
 generated_sources_dir := $(call local-generated-sources-dir)
 LOCAL_EXPORT_C_INCLUDE_DIRS := $(generated_sources_dir)/proto/system
 LOCAL_SRC_FILES := $(ue_update_metadata_protos_src_files)