This commit adds lots of plumbing to get the type section from the module linking proposal plumbed all the way through to the `wasmtime` crate and the `wasmtime-c-api` crate. This isn't all that useful right now because Wasmtime doesn't support imported/exported modules/instances, but this is all necessary groundwork to getting that exported at some point. I've added some light tests but I suspect the bulk of the testing will come in a future commit. One major change in this commit is that `SignatureIndex` no longer follows type type index space in a wasm module. Instead a new `TypeIndex` type is used to track that. Function signatures, still indexed by `SignatureIndex`, are then packed together tightly.
wasmtime-cranelfit
This crate provides an implementation of the Compiler trait which is
connected to Cranelift.