How to deal with the region crate dependency?

[bjorn3]

This crate hasn't seen any updates in almost 2 years and aside from ring is the only reason we still depend on windows-sys 0.52 from 2 years ago. And for cg_clif it is the only reason any windows-sys version other than the latest is used. windows-sys versions before last minor version ship with import libraries for each target rather than using raw-dylib. There is an open PR for region to use latest windows-sys (darfink/region-rs#38), but I don't have much faith it will be merged any time soon.

[alexcrichton]

Would it be reasonable to vendor what's necessary in the cranelift-jit crate? Wasmtime's own handling of mmaps could in theory be generalized but it's specialized enough that I'd personally probably prefer to avoid that. Do you know if it's reasonable enough to vendor/duplicate the crate within cranelift-jit?