Fixed upgrading from forward-lock application to system application

Fixes the case when the app on system is newer than the
currently installed. Something that can happen e.g. after
a FOTA update.

Change-Id: I102e9cdd5693d5e66667c0c8989dc2643c72dd16
pm: Prevent a system_server crash is package name is null

 * If an app is placed on the system partition and it doesn't specify a
   valid package name, system_server will crash forever. Just skip it.

Change-Id: I9b911d40b3c4d7cf6fac8cc0166a2ba359329b7b
Revert "[4/4] Finish fixing Zygote descriptor leakage problem"

This reverts commit cc5998e8c07a84e2efa2500448e9096f8fde65b9.