XRBK macro incorrectly handles where clauses when expanding

[Antikyth]

When splitting syn::Generics, for some reason there is a where clause component. This is strange because the generics shouldn't have a where clause - we parse that where clause separately, as we should, because it isn't always in the same place as the generics. Need to see why that component is split like that and how to do it properly.

[Antikyth]

The first easy step for this is to use the parsed where clause instead of the one split from the generics. But further research is required as to why that split where clause exists in the first place.

[Antikyth]

Potentially fixed in 74446b9, will have to see about generics being split as I say.