On Wayland, log error for failure to set cursor

The inability to set the cursor using any of the named cursor files
likely indicates an error in the system on which we are running.
'WinitPointer::set_cursor' also does not have any way of returning an
error so just log the error to assist users in diagnosing the problem.

Fixes: rust-windowing#1988.

src/platform_impl/linux/wayland/seat/pointer/mod.rs

@@ -109,9 +109,10 @@ impl WinitPointer {
         let serial = Some(self.latest_serial.get());
         for cursor in cursors {
             if self.pointer.set_cursor(cursor, serial).is_ok() {
-                break;
+                return;
             }
         }
+        warn!("Failed to set cursor to {:?}", cursor_icon);
     }
 
     /// Confine the pointer to a surface.