linux: Use pthread_setname_np instead of prctl

This function is available on Linux since glibc 2.12, musl 1.1.16, and
uClibc 1.0.20. The main advantage over `prctl` is that it properly
represents the pointer argument, rather than a multi-purpose `long`,
so we're better representing strict provenance (#95496).

library/std/src/sys/unix/thread.rs

@@ -116,11 +116,9 @@ pub fn yield_now() {
         debug_assert_eq!(ret, 0);
     }
 
-    #[cfg(any(target_os = "linux", target_os = "android"))]
+    #[cfg(target_os = "android")]
     pub fn set_name(name: &CStr) {
         const PR_SET_NAME: libc::c_int = 15;
-        // pthread wrapper only appeared in glibc 2.12, so we use syscall
-        // directly.
         unsafe {
             libc::prctl(
                 PR_SET_NAME,
@@ -132,6 +130,14 @@ pub fn set_name(name: &CStr) {
         }
     }
 
+    #[cfg(target_os = "linux")]
+    pub fn set_name(name: &CStr) {
+        unsafe {
+            // Available since glibc 2.12, musl 1.1.16, and uClibc 1.0.20.
+            libc::pthread_setname_np(libc::pthread_self(), name.as_ptr());
+        }
+    }
+
     #[cfg(any(target_os = "freebsd", target_os = "dragonfly", target_os = "openbsd"))]
     pub fn set_name(name: &CStr) {
         unsafe {