This includes the following changes:
- Limit code space to 128 MB.
- Use direct branches wherever possible.
- Where not possible, continue using load literal followed by an indirect
  branch.
- Sort RelocInfo by target_address_address for the serializer, since mixing
  load literal instructions and branch instructions messes up that order.
- Ensure we always wipe out targets in the serializer (not just for the
  snapshot) in order to be able to distinguish between constant pool entries
  and branch instructions.

Change-Id: I1a1029ce2a5f72a3a94802daf267d14a42c7c790
Reviewed-on: https://chromium-review.googlesource.com/939175Reviewed-by: Clemens Hammacher <clemensh@chromium.org>
Reviewed-by: Jaroslav Sevcik <jarin@chromium.org>
Reviewed-by: Leszek Swirski <leszeks@chromium.org>
Reviewed-by: Yang Guo <yangguo@chromium.org>
Commit-Queue: Georgia Kouveli <georgia.kouveli@arm.com>
Cr-Commit-Position: refs/heads/master@{#52885}