[LLVMdev] APFloat.h header file usage

[Chris Lattner]

> The inclusion of SerializationFwd.h can be removed by forward
> declaring the following two classes in APFloat.h:
>
> Serializer;
> Deserializer;
>
> If this doesn't seem like a clean enough solution, there are other
> ways to potentially decouple APFloat more from the Serialization
> "library."  The tradeoff is that it would require some code rewriting/
> addition, and could potentially make deserialization of APFloats (as
> done in the new C frontend) slightly less efficient.

fixed

-Chris