This requires changing the way stubs and builtins are encoded in tags, as for
arm64 we only have 26 bits to encode a PC-relative offset. With the previous
encoding scheme the builtin ids were shifted by 16 bits and ended up exceeding
this range.

Change-Id: I0f396390a622ea67b890d2dd47ca12e00092e204
Reviewed-on: https://chromium-review.googlesource.com/1059209
Commit-Queue: Georgia Kouveli <georgia.kouveli@arm.com>
Reviewed-by: Ben Titzer <titzer@chromium.org>
Reviewed-by: Clemens Hammacher <clemensh@chromium.org>
Cr-Commit-Position: refs/heads/master@{#53262}