Move zygote initialization code to the framework.

The framework class com.android.internal.os.ZygoteInit
will call back to the runtime before / after the fork, so
that it can perform runtime specific bringup / teardown.

Change-Id: I9730e12da8b22f03397658b1bddc7fd73f4fbc7d
Merge "Move zygote initialization code to the framework."
Merge remote-tracking branch 'aosp/master' into slim-master

Conflicts:
	vm/native/dalvik_system_Zygote.cpp