When creating a Code object, if it has valid builtin_index then create
its RelocInfo in RO_SPACE. For embedded builds this moves about 48 bytes
into RO_SPACE, but it's considerably more for nosnap builds.

Bug: v8:7464
Change-Id: I598cb960c0068ef4be8d72ae8f5c8d74c0195aca
Reviewed-on: https://chromium-review.googlesource.com/c/1299073Reviewed-by: Michael Lippautz <mlippautz@chromium.org>
Commit-Queue: Dan Elphick <delphick@chromium.org>
Cr-Commit-Position: refs/heads/master@{#57016}