Fix issue #4902856: Don't let apps register non-explicit PendingIntents

Location manager now checks for such intents, and logs a warning when
they are given to it.  Nothing thrown yet, it needs to check the
targetSdkVersion of the caller somehow.

When sending the pending intent, we require that the recipient hold the
appropriate permission.  This should pretty much close the security hole.

Includes a bunch of infrastructure in the activity manager needed to
support all this.

Change-Id: I4dba7a98a7b8bbb9e347666451aa9cb1efad1848