ART: Faster debug build image checks.

Rewrite `ImageChecker` to make debug build checks faster.
The `Runtime` initialization for each gtest that uses the
boot image is roughly halved on a certain low end device.

Verify only the objects in the image being added. Verifying
all heap objects was unnecessarily repeating the work for
previosly added images. (Note that chroot on-device testing
is currently using a multi-image boot image.)

Avoid read barriers as there can be no GC at that point,
make the pointer size a template argument and simplify some
other bits.

Test: m test-art-host-gtest
Test: testrunner.py --host --optimizing
Test: run-gtests.sh
Test: testrunner.py --target --optimizing
Change-Id: I44ccd8e302bde9f88844a452863365865da4ba50
1 file changed