abitidy: Add method to calculate new ids for anonymous types am: 4ccad53441 am: 1aed691eab am: 20e910e059

Original change: https://android-review.googlesource.com/c/platform/external/libabigail/+/2197899

Change-Id: I46c4a590cd4aba59171534b4d4aea72cf39238ff
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>