Revert "Revert "Stop using the runtime classpath in dex2oat""

This reverts commit 053a84b762536144d5cae309ca5abd97766b4583.

Reason for revert: Prepare the CL again to be submitted after
https://chrome-internal-review.googlesource.com/c/423809 gets merged.

Change-Id: I1d0e3d6bf2aa16249b2d0146acd9c81149924c00
3 files changed