message: add support of alloc_zeroed in LockedHeap
diff: @@ -217,6 +217,14 @@ unsafe impl GlobalAlloc for LockedHeap {
  .map_or(ptr::null_mut() as *mut u8, |mem| mem.ptr.as_ptr())
  }
  + unsafe fn alloc_zeroed(&self, layout: Layout) -> *mut u8 {
  + self.0
  + .lock()
  + .alloc(layout, AllocInit::Zeroed)
  + .ok()
  + .map_or(ptr::null_mut() as *mut u8, |mem| mem.ptr.as_ptr())
  + }
  +
  unsafe fn dealloc(&self, ptr: *mut u8, layout: Layout) {
  self.0
  .lock()
  