Move A|Rc::as_ptr from feature(weak_into_raw)

to feature(rc_as_ptr)

These were stabilized alongside the Weak versions,
but having `feature = "weak_.."` on a fn definition
for the non-weak pointers is potentially very confusing.

src/liballoc/rc.rs

@@ -1706,7 +1706,7 @@ impl<T> Weak<T> {
     /// ```
     ///
     /// [`null`]: ../../std/ptr/fn.null.html
-    #[stable(feature = "weak_into_raw", since = "1.45.0")]
+    #[stable(feature = "rc_as_ptr", since = "1.45.0")]
     pub fn as_ptr(&self) -> *const T {
         let offset = data_offset_sized::<T>();
         let ptr = self.ptr.cast::<u8>().as_ptr().wrapping_offset(offset);

src/liballoc/sync.rs

@@ -587,7 +587,7 @@ impl<T: ?Sized> Arc<T> {
     /// assert_eq!(x_ptr, Arc::as_ptr(&y));
     /// assert_eq!(unsafe { &*x_ptr }, "hello");
     /// ```
-    #[stable(feature = "weak_into_raw", since = "1.45.0")]
+    #[stable(feature = "rc_as_ptr", since = "1.45.0")]
     pub fn as_ptr(this: &Self) -> *const T {
         let ptr: *mut ArcInner<T> = NonNull::as_ptr(this.ptr);
         let fake_ptr = ptr as *mut T;