Refactor Thumb2 entrypoint adjustment handling. am: 467d570d3f am: f4d74398a5 am: a9627341cc am: d379e98afd

Original change: https://android-review.googlesource.com/c/platform/art/+/2238555

Change-Id: I52ff5892b21e391741dc4637d02e87245791318b
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>