std: replace generic thread parker with explicit no-op parker

library/std/src/sys/unsupported/mod.rs

@@ -22,6 +22,7 @@ pub mod thread;
 #[cfg(target_thread_local)]
 pub mod thread_local_dtor;
 pub mod thread_local_key;
+pub mod thread_parking;
 pub mod time;
 
 mod common;

library/std/src/sys/unsupported/thread_parking.rs

@@ -0,0 +1,11 @@
+use crate::pin::Pin;
+use crate::time::Duration;
+
+pub struct Parker {}
+
+impl Parker {
+    pub unsafe fn new_in_place(_parker: *mut Parker) {}
+    pub unsafe fn park(self: Pin<&Self>) {}
+    pub unsafe fn park_timeout(self: Pin<&Self>, _dur: Duration) {}
+    pub fn unpark(self: Pin<&Self>) {}
+}

library/std/src/sys/wasi/mod.rs

@@ -49,6 +49,8 @@ pub mod thread;
 pub mod thread_local_dtor;
 #[path = "../unsupported/thread_local_key.rs"]
 pub mod thread_local_key;
+#[path = "../unsupported/thread_parking.rs"]
+pub mod thread_parking;
 pub mod time;
 
 #[path = "../unsupported/common.rs"]

library/std/src/sys/wasm/mod.rs

@@ -70,6 +70,8 @@ cfg_if::cfg_if! {
         pub mod once;
         #[path = "../unsupported/thread.rs"]
         pub mod thread;
+        #[path = "../unsupported/thread_parking.rs"]
+        pub mod thread_parking;
     }
 }