ART: Remember whether the cache was pruned

Remember (and expose) whether the cache was pruned when initializing
the runtime.

Bug: 27618311

(cherry picked from commit 7ef1b4b20bd7cf485f5e443927c1e6fa797a0439)

Change-Id: I178d18d731a9dce5cb11ed0874c9c9c9d36d7d8e
4 files changed