Settings: Fix possible NPE

mPackageInfo and applicationInfo can sometimes be null, causing an NPE.
Check for null first and make the menu entry invisible in that case.

This commit is a squash of the following commit from CM 13.0:
29d679a1 Settings: Fix possible crash
4b03da77 Settings: Fix possible NPE

Change-Id: I4c2d73cced26b8900c95ede08e5a9c478c107529
Reference: BugDumps 13-20160715-21 L#52, BugDumps 20160909-15 L#39
(cherry picked from commit 9b525443)