Stabilize [const_]pointer_byte_offsets

Author: WaffleLapkin

tests/fail/dangling_pointers/out_of_bounds_read.rs

@@ -1,5 +1,3 @@
-#![feature(pointer_byte_offsets)]
-
 fn main() {
     let v: Vec<u16> = vec![1, 2];
     // This read is also misaligned. We make sure that the OOB message has priority.

tests/fail/dangling_pointers/out_of_bounds_write.rs

@@ -1,5 +1,3 @@
-#![feature(pointer_byte_offsets)]
-
 fn main() {
     let mut v: Vec<u16> = vec![1, 2];
     // This read is also misaligned. We make sure that the OOB message has priority.

tests/pass/provenance.rs

@@ -1,7 +1,6 @@
 //@revisions: stack tree
 //@[tree]compile-flags: -Zmiri-tree-borrows
 #![feature(strict_provenance)]
-#![feature(pointer_byte_offsets)]
 use std::{mem, ptr};
 
 const PTR_SIZE: usize = mem::size_of::<&i32>();