Remove `CompiledCode::CodePointer()`.

And clean up some related test helpers in preparation for
moving `CompiledMethod` to dex2oat/.

Test: m test-art-host-gtest
Test: run-gtests.sh
Change-Id: I13b42bfb4f6ee3a7f7f22bbc8d22203c5d56e00b
6 files changed