_ReadWriteBarrier() deprecated

[Exaelitus]

FYI- Should probably replace its usage in MeowHash

https://docs.microsoft.com/en-us/cpp/intrinsics/readwritebarrier?view=vs-2019

[NoHatCoder]

And how does that work out if you want a C compatible library?

[cmuratori]

It is probably safe to just remove this entirely. It was simply an attempt to get Microsoft's codegen to do something more logical, but it is not really necessary. When I get a chance, I will be checking in explicit optimal ASM versions of Meow anyways, so there's really no need to try to have the C version produce optimal ASM anymore. Anyone who needs ASM-perfect Meow can just use the ASM files.

- Casey