Rollup merge of #62414 - jethrogb:jb/sgx-uninit, r=Mark-Simulacrum

Remove last use of mem::uninitialized in SGX

See #62397

src/libstd/sys/sgx/mod.rs

@@ -3,8 +3,6 @@
 //! This module contains the facade (aka platform-specific) implementations of
 //! OS level functionality for Fortanix SGX.
 
-#![allow(deprecated)]
-
 use crate::io::ErrorKind;
 use crate::os::raw::c_char;
 use crate::sync::atomic::{AtomicBool, Ordering};
@@ -142,7 +140,7 @@ pub unsafe extern "C" fn __rust_abort() {
 pub fn hashmap_random_keys() -> (u64, u64) {
     fn rdrand64() -> u64 {
         unsafe {
-            let mut ret: u64 = crate::mem::uninitialized();
+            let mut ret: u64 = 0;
             for _ in 0..10 {
                 if crate::arch::x86_64::_rdrand64_step(&mut ret) == 1 {
                     return ret;