ART: Correctly handle temporary classes in class-load events (2/3)

When a temporary class is given out in a ClassLoad event, all stored
references need to be fixed up before publishing a ClassPrepare event.

This CL handles objects stored as local references.

Bug: 31684920
Test: m test-art-host-run-test-912-classes
Change-Id: I3c6bbfdaca31d0c0d8ae9bf1facef404e949b6aa