Allow unresolved exception classes in boot image.

And incorporate dex2oat_image_test changes from
    https://android-review.googlesource.com/1302586
to test that this works.

Test: m test-art-host-gtest
Bug: 153648261
Change-Id: I810de9c84973156c06a2c871bf2e0921c80a3fa4
2 files changed