This commit implements the interpretation necessary of the instance section of the module linking proposal. Instantiating a module which itself has nested instantiated instances will now instantiate the nested instances properly. This isn't all that useful without the ability to alias exports off the result, but we can at least observe the side effects of instantiation through the `start` function. cc #2094
This is the wasmtime-jit crate, which contains JIT-based execution
for wasm, using the wasm ABI defined by wasmtime-environ and the
runtime support provided by wasmtime-runtime.
Most users will want to use the main wasmtime crate instead of using this
crate directly.