Correct vulnerability when setting pending intents on import/export notifications by setting FLAG_IMMUTABLE

For cases where we were setting an empty content intent, setContentIntent has not been required since Gingerbread

Bug: 161718556
Test: build
Change-Id: I1f62fdc077401fea2c48a31527464464f08a6b64
(cherry picked from commit 1d595f80e9c5157f8ca0285b572c9f1463e05c58)
2 files changed