Build wasi-libc library on Windows since libuv may be not supported. This PR is a first step
to make it working, but there's still a number of changes to get it fully working.
This folder contains the platform abstract layer for multiple platforms. To support a new platform, you can simply create a new folder here and implement all the APIs defined in include folder.
Refer to port_wamr.md for how to port WAMR to a target platform.