Uses ptr::from_ref in pi_mutex.rs

We have new API for casting now.

Author: ruihe774

library/std/src/sys/pal/unix/pi_futex.rs

@@ -1,9 +1,8 @@
 #![cfg(any(target_os = "linux", target_os = "android"))]
 
-use crate::io;
-use crate::ptr::null;
 use crate::sync::atomic::AtomicU32;
 use crate::sys::cvt;
+use crate::{io, ptr};
 
 pub const fn unlocked() -> u32 {
     0
@@ -26,10 +25,10 @@ pub fn futex_lock(futex: &AtomicU32) -> io::Result<()> {
         match cvt(unsafe {
             libc::syscall(
                 libc::SYS_futex,
-                futex as *const AtomicU32,
+                ptr::from_ref(futex),
                 libc::FUTEX_LOCK_PI | libc::FUTEX_PRIVATE_FLAG,
                 0,
-                null::<u32>(),
+                ptr::null::<u32>(),
                 // remaining args are unused
             )
         }) {
@@ -44,7 +43,7 @@ pub fn futex_unlock(futex: &AtomicU32) -> io::Result<()> {
     cvt(unsafe {
         libc::syscall(
             libc::SYS_futex,
-            futex as *const AtomicU32,
+            ptr::from_ref(futex),
             libc::FUTEX_UNLOCK_PI | libc::FUTEX_PRIVATE_FLAG,
             // remaining args are unused
         )