message: unlikely in Alloca
  Summary:
  Mark a branch `unlikely` in `Alloca`.
  Should have no effect, just to be safe.
diff: use std::{
  alloc::{alloc, dealloc, Layout},
  cell::{Cell, RefCell},
  - intrinsics::likely,
  + intrinsics::{likely, unlikely},
  mem,
  mem::MaybeUninit,
  ptr, slice,
  @@ -101,7 +101,7 @@ impl Alloca {
  let mut start = self.alloc.get();
  let mut stop = start.wrapping_add(size_words);
  - if stop > self.end.get() {
  + if unlikely(stop > self.end.get()) {
  self.allocate_more(layout);
  start = self.alloc.get();
  stop = start.wrapping_add(size_words);
  