Add FLAG_IMMUTABLE flag to PendingIntent.

It is required to specify the PendingIntent mutability flag strart from Android S.

Bug: 178086680
Test: atest CtsAppTestCases:android.app.cts.ServiceTest#testForegroundService_pendingIntentForeground
Change-Id: I51b67e07d6c04afe3a93d559eaccb0627c224c7e
1 file changed