pm: Don't throw if invalid package setting or classname.

  Since an application could be updating in the background while
  the query for isComponentProtected occurs, the package setting
  for it can be null. Instead of throwing here, return false.

Change-Id: Idb8f11785961ddf2b567e93977a9ca4650ab2119
TICKET: CYNGNOS-2689
(cherry picked from commit 25550fba)
(cherry picked from commit 0dae9f75)