In a couple of places we cast between uintptr_t and uint64_t with a
reinterpret_cast. While this is correct when these types are aliased
to the same type, if they are defined to be different integral types
(while still of the same size), reinterpet_cast won't work.

Change-Id: I6e935c6c263d8df16f88659ac285faeb5e073add
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2614678Reviewed-by: Ross McIlroy <rmcilroy@chromium.org>
Commit-Queue: Georgia Kouveli <georgia.kouveli@arm.com>
Cr-Commit-Position: refs/heads/master@{#71988}