Fix logic to find dex2oat.

On device, we now have dex2oat64/dex2oat32 with no symlinks, so be
explicit on the bitness when trying to find the executable.

Bug: 153380900
Test: run-gtests.sh, testrunner.py, run-libcore-tests, run-libjdwp-tests
Change-Id: I796eedc84d75aaa2a525d3ed2cbcbe157e5220fb
5 files changed