Building std for wasm32-wasip3 fails due to missing target_env = "p3" in library/std/src/os/mod.rs

Problem Description

When compiling std for wasm32-wasip3 (e.g. ./x.py build --target wasm32-wasip3 library/std), the build fails with 13 compilation errors starting with cannot find wasi in os:

error[E0433]: cannot find `wasi` in `os`
  --> library/std/src/os/fd/raw.rs:24:16
   |
24 | use crate::os::wasi::io::OwnedFd;
   |                ^^^^ could not find `wasi` in `os`
   |
note: found an item that was configured out
  --> library/std/src/os/mod.rs:58:17
   |
57 |         #[cfg(any(target_env = "p1", target_env = "p2"))]
   |                  -------------------------------------- the item is gated here
58 |         pub mod wasi;
   |                 ^^^^

Cause

In Rust 1.98.0, library/std/src/os/mod.rs was refactored with cfg_select!. In 1.97.x, pub mod wasi; was declared as:

#[cfg(any(target_os = "wasi", any(target_env = "p1", target_env = "p2"), doc))]
pub mod wasi;

In 1.98.0, this was changed to:

    target_family = "wasm" => {
        #[cfg(any(target_env = "p1", target_env = "p2"))]
        pub mod wasi;
        #[cfg(target_env = "p2")]
        pub mod wasip2;
    }

This omitted target_os = "wasi" / target_env = "p3". Since wasm32-wasip3 has target_family = "wasm", target_os = "wasi", and target_env = "p3", pub mod wasi; is configured out, breaking internal modules (sys/fs/unix.rs, sys/env/wasi.rs, os/fd/raw.rs) that depend on crate::os::wasi::*.

Proposed Fix

--- a/library/std/src/os/mod.rs
+++ b/library/std/src/os/mod.rs
@@ -54,7 +54,7 @@
         pub mod linux;
     }
     target_family = "wasm" => {
-        #[cfg(any(target_env = "p1", target_env = "p2"))]
+        #[cfg(any(target_os = "wasi", target_env = "p1", target_env = "p2", target_env = "p3"))]
         pub mod wasi;
         #[cfg(target_env = "p2")]
         pub mod wasip2;

Start in library/std/src/os/mod.rs at the target_family = "wasm" cfg_select! block and compare its wasi module condition with the issue description. Run ./x.py build --target wasm32-wasip3 library/std to reproduce the missing wasi errors. Done means std builds for wasm32-wasip3 without those compilation errors.