Wasmtime has a few representations of `Val` and `ValType` across the
internal crates, the `wasmtime` crate, and the C API. These were
previously sometimes mentioned in different orders which means that
converting between the two took a little extra code than before. This
commit is a micro-optimization to align the types across the various
places we define these to help reduce the codegen burden when converting
between these types.
This is not expected to have a major impact on performance, rather it's
a small cleanup which should be easy-ish to preserve I've noticed while
staring at assembly.
c33700087d