const_eval_select: add tracking issue

Author: RalfJung

library/core/src/intrinsics.rs

@@ -2661,8 +2661,7 @@ extern "rust-intrinsic" {
 ///
 /// Currently such an assertion would always succeed; until Rust decides
 /// otherwise, that principle should not be violated.
-#[rustc_const_unstable(feature = "const_eval_select", issue = "none")]
-#[unstable(feature = "core_intrinsics", issue = "none")]
+#[rustc_const_unstable(feature = "const_eval_select", issue = "124625")]
 #[cfg(not(bootstrap))]
 #[rustc_intrinsic]
 #[rustc_intrinsic_must_be_overridden]