std: replace pthread RwLock with custom implementation inspired by usync

Author: joboet

library/std/src/lib.rs

@@ -339,12 +339,14 @@
 #![feature(portable_simd)]
 #![feature(prelude_2024)]
 #![feature(ptr_as_uninit)]
+#![feature(ptr_mask)]
 #![feature(slice_internals)]
 #![feature(slice_ptr_get)]
 #![feature(slice_range)]
 #![feature(std_internals)]
 #![feature(str_internals)]
 #![feature(strict_provenance)]
+#![feature(strict_provenance_atomic_ptr)]
 // tidy-alphabetical-end
 //
 // Library features (alloc):

library/std/src/sys/pal/unix/locks/mod.rs

@@ -22,10 +22,10 @@ cfg_if::cfg_if! {
         pub(crate) use futex_condvar::Condvar;
     } else {
         mod pthread_mutex;
-        mod pthread_rwlock;
         mod pthread_condvar;
+        mod queue_rwlock;
         pub(crate) use pthread_mutex::Mutex;
-        pub(crate) use pthread_rwlock::RwLock;
+        pub(crate) use queue_rwlock::RwLock;
         pub(crate) use pthread_condvar::Condvar;
     }
 }