wasmtime-environ is meant to support cross compilation, so it shouldn't have dependencies on target layout of structs. This moves the layout back into wasmtime-execute, and adds a system of asserts for checking that wasmtime-environ's offsets stay in sync.
This is the wasmtime-environ crate, which contains the implementations
of the ModuleEnvironment and FuncEnvironment traits from
cranelift-wasm. They effectively
implement an ABI for basic wasm compilation, which can be used for JITing,
native object files, or other purposes.