Add ClassLoader to app-image roots.

Previously we were looking for class loaders by going
through the dex cache type array. When we change the array
to be hash-based, we may not actually find the class loader
that way.

Bug: 30627598
Test: m test-art-host
Change-Id: Ic91a81853fec9946e26bb8272d2a9120393a43bf
5 files changed