system/core: add libpackagelistparser

There are 4 components that all implement package parsing, they are:
1. sdcardd
2. libselinux
3. logd
4. runas

Create a library that can be used by all of them, and new ones as needed.

(Moved from frameworks/base)

Change-Id: I282ec1204e592502ef3b28fedf577af824338c58