ART: Prune FindArrayClass cache in image writer

The ClassLinker cache speeds up FindArrayClass requests, but all
entries are roots. It is possible that an entry is a non-image
class when creating the boot image, artificially keeping the
class around.

Bug: 21596650

(cherry picked from commit 44905ce1c97613a5cb44046049843fe1029a64cf)

Change-Id: Ief9b439945d0e293a3cb5dcddfeb189b5e174f06
3 files changed