<intrin0.h>: needs some stuff for `_M_ARM64`

For https://github.com/microsoft/STL/pull/2127 I need

1) `__uint64ToN64_v`
2) `neon_cnt`
3) `neon_addv8`
4) `__n64`

from `<arm64_neon.h>`

https://godbolt.org/z/MbEqfshGG