[builtins] Fix gcc compilation error

Not using constexpr might throw this error during compilation:

```
error: call to non-'constexpr' function 'std::__1::array<_Tp, ...
```

Bug: v8:11420
Change-Id: I308e76b9d9683ae37088ef8e1a5d72cd1e05de78
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2930362


Reviewed-by: Camillo Bruni <cbruni@chromium.org>
Reviewed-by: Santiago Aboy Solanes <solanes@chromium.org>
Commit-Queue: Camillo Bruni <cbruni@chromium.org>
Cr-Commit-Position: refs/heads/master@{#74905}