f44fe25f9c
The memmap crate doesn't make it straightforward to have part of the region be writeable and part readonly. Since this is a fairly boutique use case, and we don't need all that much code, just use the low-level APIs directly. Also, introduce a concept of "tunables" for adjusting the parameters of the runtime.
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.