This commit enables `wasmtime_runtime::Table` to internally hold elements of either `funcref` (all that is currently supported) or `externref` (newly introduced in this commit). This commit updates `Table`'s API, but does NOT generally propagate those changes outwards all the way through the Wasmtime embedding API. It only does enough to get everything compiling and the current test suite passing. It is expected that as we implement more of the reference types spec, we will bubble these changes out and expose them to the embedding API.
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.