Properly track interface roots in AnonymousClassMerging
Properly track interface roots in AnonymousClassMerging

Summary: Make the roots metrics more consistent between `AnonymousClassMerging` and `IntraDexClassMerging`

Reviewed By: NTillmann

Differential Revision: D37217733

fbshipit-source-id: 27448abcac33cc928618dfd196e22e0f0886621a

facebook/redex,facebook/redex,facebook/redex,facebook/redex,facebook/redex,facebook/redex,facebook/redex,facebook/redex,facebook/redex