Rollup merge of #140511 - mathisbot:master, r=dtolnay

Stabilize `#![feature(non_null_from_ref)]`

This PR stabilizes the following:
```rust
impl<T: ?Sized> NonNull<T> {
    pub const fn from_ref(reference: &T) -> NonNull<T>;
    pub const fn from_mut(reference: &mut T) -> NonNull<T>;
}
```
The feature is tracked in [#130823](#130823).

Author: fmease

library/core/src/lib.rs

@@ -111,7 +111,6 @@
 #![feature(is_ascii_octdigit)]
 #![feature(lazy_get)]
 #![feature(link_cfg)]
-#![feature(non_null_from_ref)]
 #![feature(offset_of_enum)]
 #![feature(panic_internals)]
 #![feature(ptr_alignment_type)]

library/core/src/ptr/non_null.rs

@@ -262,15 +262,17 @@ impl<T: ?Sized> NonNull<T> {
     }
 
     /// Converts a reference to a `NonNull` pointer.
-    #[unstable(feature = "non_null_from_ref", issue = "130823")]
+    #[stable(feature = "non_null_from_ref", since = "CURRENT_RUSTC_VERSION")]
+    #[rustc_const_stable(feature = "non_null_from_ref", since = "CURRENT_RUSTC_VERSION")]
     #[inline]
     pub const fn from_ref(r: &T) -> Self {
         // SAFETY: A reference cannot be null.
         unsafe { NonNull { pointer: r as *const T } }
     }
 
     /// Converts a mutable reference to a `NonNull` pointer.
-    #[unstable(feature = "non_null_from_ref", issue = "130823")]
+    #[stable(feature = "non_null_from_ref", since = "CURRENT_RUSTC_VERSION")]
+    #[rustc_const_stable(feature = "non_null_from_ref", since = "CURRENT_RUSTC_VERSION")]
     #[inline]
     pub const fn from_mut(r: &mut T) -> Self {
         // SAFETY: A mutable reference cannot be null.