This adds initial, unstable, support for the wasm32-wasi target. Not all of Tokio's
features are supported yet as WASI's non-blocking APIs are still limited.
Refs: tokio-rs/tokio#4827
The `&mut self` requirements for `TcpStream` methods ensure that there are at
most two tasks using the stream--one for reading and one for writing.
`TcpStream::split` allows two separate tasks to hold a reference to a single
`TcpStream`. `TcpStream::{peek,poll_peek}` only poll for read readiness, and
therefore are safe to use with a `ReadHalf`.
Instead of duplicating `TcpStream::poll_peek`, a private method is now used by
both `poll_peek` methods that uses the fact that only a `&TcpStream` is
required.
Closes#2136
A step towards collapsing Tokio sub crates into a single `tokio`
crate (#1318).
The `net` implementation is now provided by the main `tokio` crate.
Functionality can be opted out of by using the various net related
feature flags.
tiif