Improve readability in the VUops.

Also remove large min/max defines which can be reduced to std::min/std::max on a ternary.

If you don't like defines, the function equivalent would be:
```
inline u32 fp_max(s32 a, s32 b) {
	return (a < 0 && b < 0) ? std::min(a, b) : std::max(a, b);
}
```