Refactor Thumb2 entrypoint adjustment handling. am: 467d570d3f am: f4d74398a5 am: a9627341cc am: d379e98afd am: e1a2d2f856

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

Change-Id: I67ede5c19ed22b085bc99556887e7cac621fbcc4
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>