[ActivityManager] Prevent coredump file may not complete for testing.

Cherry-pick from aosp to lmp-dev

Sympton:
During testing, skip kill native crash process manually because it
will continue to die by default.

Root Cause:
Large process may take some time to do coredump.In auto test, crash
process will be killed immediately that results incomplete coredump
file.

Solution:
If the tester (IActivityController) will handle app crash event,
Do not kill native crashed process if the rom is debuggable.

Change-Id: Ia360af147d694125d440e5ba2f958c4759a50494

Conflicts:
	services/java/com/android/server/am/ActivityManagerService.java