Fix MSVC Win32 count_digits

[upsj]

We are shifting past 32 bit since the integer literals are 32 bits wide.

Additionally, it looks like having the constexpr table inside the function leads to pretty bad codegen on MSVC, so it might make sense to move it outside the function, though I didn't include that here since I don't know how you deal with constexpr globals

[vitaut]

Thank you!

As for the table, an easy fix is to make it static on MSVC (it cannot be made static unconditionally because of some clang quirk).

[upsj]

Yeah, I noticed the same thing. Not sure whether the standard allows it, but constexpr static would be what I would ideally want to use