SkSplicer: fix aarch64 jump offset, turn on testing on aarch64 Android bots

I also updated the dump feature to work with aarch64, and included comments on how to disassemble an aarch64 dump.

Looking at an aarch64 dump made it immediately obvious that the jump offset was off by 1.

Change-Id: I17fa6ee44779e8be69ab4582e338c88212aba36c
Reviewed-on: https://skia-review.googlesource.com/6841
Reviewed-by: Herb Derby <herb@google.com>
Commit-Queue: Mike Klein <mtklein@chromium.org>
2 files changed