This reverts commit 0c63aa9e.

Reason for revert: Breaking clusterfuzz builds

Original change's description:
> [ptr-cage] Reserve base registers on x64 (r14) and arm64 (x28)
>
> Also add a V8_COMPRESS_POINTERS_IN_SHARED_CAGE define when pointer
> compression is enabled.
>
> This CL is to get performance numbers for reserving an extra register.
> There is no actual pointer cage yet, and the base register will always
> have the same value as the root register. The pointer decompression code
> is switched to using the base register instead of the root register.
>
> Bug: v8:11460
> Change-Id: I40bae556c2098608fb6fc193a52694e3f54754bd
> Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2716075
> Reviewed-by: Jakob Kummerow <jkummerow@chromium.org>
> Reviewed-by: Ross McIlroy <rmcilroy@chromium.org>
> Reviewed-by: Leszek Swirski <leszeks@chromium.org>
> Commit-Queue: Shu-yu Guo <syg@chromium.org>
> Cr-Commit-Position: refs/heads/master@{#73204}

Bug: v8:11460
Change-Id: Idebf1fc6eeeda880a21d65b6f2c674fa58690bfa
No-Presubmit: true
No-Tree-Checks: true
No-Try: true
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2737812
Auto-Submit: Shu-yu Guo <syg@chromium.org>
Commit-Queue: Rubber Stamper <rubber-stamper@appspot.gserviceaccount.com>
Bot-Commit: Rubber Stamper <rubber-stamper@appspot.gserviceaccount.com>
Cr-Commit-Position: refs/heads/master@{#73205}