frameworks/base: Port of approved stability fixes to GB

Implement Mutual exclusion in BroadcastReceiver, Invoke
forceStopPackageLocked only after acquiring a lock on
ActivityManagerService.this.

ServiceRecord's bindings is a hashmap to keep track of all active
bindings to the service. This is not cleared when the service is
brought down by activity manager. This adds up the references to
IntentBindRecords and its references to ServiceRecord. Fix is to
clear the bindings.

ServiceRecord's restarter is a reference to the service and is not
cleared when the service is brought down by activity manager. This
adds up the references to ServiceRecord. Fix is to set the reference
to null when the service is brought down by activity manager.

The service connection to the previous live wallpaper is unbound when
a new wallpaper is effective. Although the service connection is
unbound it is not disconnected and its reference to wallpaper's
service and engine is still effective. This adds up to the total
JNI references and causes dalvik (hosting system_server) to abort.
Fix is to release the references in clearWallpaperComponentLocked.

startActivityUncheckedLocked tries to move the target task to front
when it is not at front. topRunningNonDelayedActivityLocked is used
to find the current task, however null value isn't handled. This
null causes an unhandled exception leading to the android framework
reboot.

Change-Id: I31349a421b32148cbce750e3531bb749f9a917a9