Emulator: enable predexopt for some sample apps

Some sample apps on emulator are placed on /data
partition and are not pre-dexopted.
Enable them to make the emulator system image a
little faster, especially for arm.
bug: 28312444

This should only impact SDK system images, not
real devices.

Change-Id: Icdb34512a3a6d95b4d6ffd2415835c6ba8c77fcc
5 files changed