After compilation there's actually no need to hold onto the native signature for a wasm function type, so this commit moves out the `ir::Signature` value from a `Module` into a separate field that's deallocated when compilation is finished. This simplifies the `SignatureRegistry` because it only needs to track wasm functino types and it also means less work is done for `Func::wrap`.
wasmtime-cranelfit
This crate provides an implementation of the Compiler trait which is
connected to Cranelift.