Update rules to install JNI libraries.

Previously we have to use LOCAL_REQUIRED_MODULES to install jni
libraries for an apk in bundled build.
With this change, we'll use LOCAL_JNI_SHARED_LIBRARIES alone to
install jni shared libraries.

The new rules are:
- If we are doing unbundled build, or the apk isn't going to be
  installed to system partitions, we'll embed the jni libs in the
  built apk.
- Otherwise, the jni libraries will be installed to the system
  lib path, and symlinks created in the app specific lib path.

Change-Id: Id6bd5301eb632bda3593664acee580f0d8b1d5d4