tokio: enable rt-multi-thread for wasm32-wasi-preview1-threads target

[Brooooooklyn]

Motivation

Enable rt-multi-thread for wasm32-wasi-preview1-threads target

[Darksonn]

How do these target names interact with #6484?

[Brooooooklyn]

we can change the wasm32-wasi-preview1-threads to wasm32-wasip1-threads after the name changed

[Darksonn]

Thank you.

[namse]

@Darksonn Hello! I'm in need of this particular feature, however it does not appear to have been released yet. Would you happen to know if there is an expected timeframe for when it might become available?

[Darksonn]

This week.

[edusporto]

I'm trying to compile a project with the feature rt-multi-thread with target --target=wasm32-wasip1-threads on tokio 1.39.3, which should have this feature as per this PR, but I'm getting the following error:

error: Only features sync,macros,io-util,rt,time are supported on wasm.
   --> /Users/me/.cargo/registry/src/index.crates.io-6f17d22bba15001f/tokio-1.39.3/src/lib.rs:467:1
    |
467 | compile_error!("Only features sync,macros,io-util,rt,time are supported on wasm.");
    | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

The full command I'm running to get it to compile is:

RUSTFLAGS='-L /opt/wasi-sdk-24.0/share/wasi-sysroot/lib/wasm32-wasip1-threads -lstatic=c++ -lstatic=c++abi' CXXSTDLIB=c++ CC=/opt/wasi-sdk-24.0/bin/clang CXX=/opt/wasi-sdk-24.0/bin/clang++ CXXFLAGS="-fno-exceptions" CFLAGS="-Wno-everything" cargo build --release --target=wasm32-wasip1-threads

Am I missing something? It seems like it should be working since this PR was merged in v1.38.0

[Darksonn]

It's unstable. Please see the docs for information on using unstable features.