Linux symbol CRCs: support 0 and report presence changes am: 2dcbaeb094 am: a8a3fc77ab

Original change: https://android-review.googlesource.com/c/platform/external/libabigail/+/2252144

Change-Id: I36748298ebf1ca85e3fdb648f216e98711410fd1
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>