Add boot image checksums to image header.

This adds an early validity check, so that we do not need to
load an image extension and oat file before we can discard
them as out-of-date based on the checksums from oat header.

Test: m test-art-host-gtest
Test: testrunner.py --host --optimizing --interp-ac
Bug: 119800099
Change-Id: I951e8429f8dde73f3fc41c36dffe5a657a0db62b
6 files changed