This reverts commit d607f1e7.

Reason for revert: Suspected cause of hanging tests:

https://bugs.chromium.org/p/v8/issues/detail?id=6927#c13

Original change's description:
> [Memory] Move GetRandomMmapAddr from base::OS platform to v8::internal.
> 
> - Moves GetRandomMmapAddr from platform to v8::internal allocation
>   primitives, in preparation for delegating this to the embedder.
> - Adds hint parameters to OS functions that used to use this function.
> 
> Bug: chromium:756050
> Cq-Include-Trybots: master.tryserver.chromium.linux:linux_chromium_rel_ng
> Change-Id: Iad72e6eac9c08a3e22c2cd2b2905623b8e514ae0
> Reviewed-on: https://chromium-review.googlesource.com/677777
> Reviewed-by: Ulan Degenbaev <ulan@chromium.org>
> Commit-Queue: Bill Budge <bbudge@chromium.org>
> Cr-Commit-Position: refs/heads/master@{#48124}

TBR=bbudge@chromium.org,ulan@chromium.org

# Not skipping CQ checks because original CL landed > 1 day ago.

Bug: chromium:756050
Change-Id: I2c515934906e67b47ceea2863bc2992ac1d23ab3
Cq-Include-Trybots: master.tryserver.chromium.linux:linux_chromium_rel_ng
Reviewed-on: https://chromium-review.googlesource.com/726319
Commit-Queue: Bill Budge <bbudge@chromium.org>
Reviewed-by: Bill Budge <bbudge@chromium.org>
Reviewed-by: Ulan Degenbaev <ulan@chromium.org>
Cr-Commit-Position: refs/heads/master@{#48701}