Perform zipalign-on-install of applications.

This change has a few components.

1. Build zipalign for the target.
2. Don't start the AppDirObservers until after scanDirLI completes
3. Execute zipalign from installd before performing a dexopt.

Conflicts:

	services/java/com/android/server/PackageManagerService.java

Change-Id: I1ab6feaf288185c9a133791d44a2e84f58048da4