Mark jni libs as REQUIRED by their app

This makes the dependencies of the jni lib .so appear in
product_target_FILES. Previously, only the jni lib .so
itself appeared, as an effect of being added to the
INSTALLED files of the app.

Bug: 129323707
Test: compare the output between `m dump-files` and installed-files.txt
Test: noop in terms of build artifacts
Change-Id: Ie391bb45ad7758e51368cabb1ecba5caeae2f09c