Avoid marking proxy class as erroneous twice.

This code path was missed in
    https://android-review.googlesource.com/102184 .

(cherry picked from commit a4d28dd66683c1bc27ad936d30aee71e73b084db)

Test: m test-art-host-gtest
Test: testrunner.py --host --optimizing
Bug: 192246059
Merged-In: Ie41c3d55b76667b186dc47999e024372669764f9
Change-Id: I17b24d9d0b71959e778376fa6ef4fe2dc482b122