Compiler changes for boot image extension.

Test: m test-art-host-gtest
Test: testrunnner.py --host --optimizing
Test: aosp_taimen-userdebug boots.
Test: run-gtest.sh
Test: testrunner.py --target --optimizing
Change-Id: I8e999c96ec908f26d8c529edc9d2a3be49a9379a
13 files changed