The purpose of this change is to add read access control to the property
space.
In the current design, a process either has access to the single
/dev/__properties__ file and therefore all properties that it contains
or it has access to no properties. This change separates properties
into multiple property files based on their selabel, which allows
creation of sepolicies that allow read access of only specific sets of
properties to specific domains.
Bug 21852512
Change-Id: Ice265db79201ca811c6b6cf6d851703f53224f03
49a309ff6a