Similar to other data structures owned by the `Store` there's no need for `Instance` to have a strong `Arc` reference, instead it's sufficient for `Store` to have the owning reference.
This is the wasmtime-runtime crate, which contains wasm runtime library
support, supporting the wasm ABI used by wasmtime-environ,
wasmtime-jit, and wasmtime-obj.
This crate does not make a host vs. target distinction; it is meant to be compiled for the target.
Most users will want to use the main wasmtime crate instead of using this
crate directly.