message: Replace most uses of `pointer::offset` with `add` and `sub`
diff: @@ -94,7 +94,7 @@ mod platform {
  struct Header(*mut u8);
  const HEAP_ZERO_MEMORY: DWORD = 0x00000008;
  unsafe fn get_header<'a>(ptr: *mut u8) -> &'a mut Header {
  - &mut *(ptr as *mut Header).offset(-1)
  + &mut *(ptr as *mut Header).sub(1)
  }
  unsafe fn align_ptr(ptr: *mut u8, align: usize) -> *mut u8 {
  let aligned = ptr.add(align - (ptr as usize & (align - 1)));
  