Issue 13052 - TypeInfo.getHash should return same hash for different floating point zeros

https://issues.dlang.org/show_bug.cgi?id=13052
Why does `float` have a special case here? Wouldn't it be better to just use `hashOf` for everything?
Also, should this be made CTFE-able? If not, are we guaranteed to have consistent hashing behaviour of floats in CTFE vs. runtime?