This reverts commit cee2f772.

Reason for revert: Breaks sanitizer builds: https://ci.chromium.org/p/v8/builders/luci.v8.ci/V8%20Linux64%20UBSan/4682

Original change's description:
> [build] disable C++ optimization for mksnapshot code.
> 
> By disabling C++ optimizations for code that's only run in mksnapshot,
> that is, CSA and Torque-generated code, we can save compile time.
> I observed up to 2x improvements of compile time for some files,
> while the mksnapshot time did not increase significantly.
> 
> Bug: v8:7629
> Change-Id: I96be2966611b2471b68023e0dd9e351d94f0013c
> Reviewed-on: https://chromium-review.googlesource.com/c/1460941
> Reviewed-by: Yang Guo <yangguo@chromium.org>
> Reviewed-by: Sigurd Schneider <sigurds@chromium.org>
> Commit-Queue: Tobias Tebbi <tebbi@chromium.org>
> Cr-Commit-Position: refs/heads/master@{#59585}

TBR=yangguo@chromium.org,sigurds@chromium.org,tebbi@chromium.org

Change-Id: I50da40da167f49a14e3a8994377c4f9dafdfe2ab
No-Presubmit: true
No-Tree-Checks: true
No-Try: true
Bug: v8:7629
Reviewed-on: https://chromium-review.googlesource.com/c/1472630Reviewed-by: Tobias Tebbi <tebbi@chromium.org>
Commit-Queue: Tobias Tebbi <tebbi@chromium.org>
Cr-Commit-Position: refs/heads/master@{#59586}