Check bg persistent-app policy against base uid, not nominal

SysUI, for example, needs to be able to start services in secondary
users, and in those users they run as the user-appropriate decorated
uid.

Bug 35200453
Test: verify user switch behavior via logging

Change-Id: Ia154f140e315fd97aed414c6444ba550632eb610
(cherry picked from commit 7408813e3cea3bf553028a0e8e272ec96473ba41)
1 file changed