Avoid locking mChanges when not necessary

This is done to prevent a deadlock from occuring when PackageManager#getApplicationInfo is called while mChanges is locked.

Bug: 190058852
Test: atest FrameworksServicesTests:CompatConfigTest
Merged-in: I193c8f0ce2659b89469bb21e505a6da382b64703
Change-Id: I193c8f0ce2659b89469bb21e505a6da382b64703