Add option for duplicate classes check to return all dupes.

When verbose oat is enabled, duplicate classes check will not stop at
the first duplicate found, outputting all duplicates found.
Can be enabled via: adb shell setprop dalvik.vm.extra-opts -verbose:oat

Test: mm test-art-host
Change-Id: If1cd55e2ad18fa4bb12d9237e18735ee0f89840b