YJIT: Fix unused_unsafe warning in StatsAlloc

Merged: https://github.com/ruby/ruby/pull/15368

jit/src/lib.rs

@@ -1,4 +1,5 @@
 //! Shared code between YJIT and ZJIT.
+#![warn(unsafe_op_in_unsafe_fn)] // Adopt 2024 edition default when targeting 2021 editions
 
 use std::sync::atomic::{AtomicUsize, Ordering};
 use std::alloc::{GlobalAlloc, Layout, System};