When typechecking macros, we need to pass along `FunValue`s also for value-like macro expressions

[dschrempf]

We need these FunValues, for example, to compute the lengths of vectors statically. That is, when inferring the type of a type-like macro expression, we need to compute the FunValue.

However, when typechecking a value-like macro expression, we do not need to pass along FunValues.

See TODO item in the code.

[edsko]

Closely related to #7.

[edsko]

Turns out it makes sense to fix this as part of well-typed/hs-bindgen#1952 .