Allow files generated by droidstubs to be copied in the SDK

We need to get files generated by a droidstubs target into the SDK. So
we first copy them into the out/target/common/obj/PACKAGING folder where
they can be picked up by the SDK build.

Bug: 142480924
Test: m sdk
Change-Id: I7a0b22907603e1d17ac05901ee7f8bb9cff89f7f
diff --git a/core/Makefile b/core/Makefile
index f02eb19..47d163e 100644
--- a/core/Makefile
+++ b/core/Makefile
@@ -5080,6 +5080,7 @@
 	$(target_notice_file_txt) \
 	$(tools_notice_file_txt) \
 	$(OUT_DOCS)/offline-sdk-timestamp \
+	$(SDK_METADATA_FILES) \
 	$(SYMBOLS_ZIP) \
 	$(COVERAGE_ZIP) \
 	$(APPCOMPAT_ZIP) \