Remove unnecessary files when installing.

We don't need the stub shared libraries since the platform build
already generates those, and we don't want the Android.bp files (we
should start purging these as part of the NDK build, but we don't
right now).

Test: Re-ran previous update command, verified no changes.
Bug: None
Change-Id: I544cf272d262e4b8fa638165d8202b3538fb0772