Parcelable getStability SystemApi MODULE_LIBRARIES

This method is intentionally overridden by subclasses. The
infrastructure doesn't detect that this is happening, but we should
still annotate this as part of the API.

As requested by API review council.

Bug: 162811168
Test: build only
Change-Id: I27714a93b71108cc0cc62fc858c260e2a6920ba9