Compiling internal_math.hpp failed in some Visual Studio

[yosupo06]

Reporter: TumoiYorozu (Japanese tweet: https://twitter.com/TumoiYorozu/status/1303198406513291264 )

It seems that some Visual Studio failed to compile internal_math. We need to take a look into.

As a temporary solution, replacing

    for (long long a : {2, 7, 61}) {

into

    int v[] = { 2, 7, 61 };
    for (long long a : v) {

works, but we have to find the reason.

[yosupo06]

I got the reason.

In default, the project of Visual Studio enables the SDL check (/sdl).
However, we run MSVC from cmake & CLI, so don't enable this.

And somehow SDL check breaks above code (related?: https://stackoverflow.com/questions/42917099/constexpr-errors-vs2017-c-compiler-regression)