Warning symbols are overwritten by cloud glyphs

[hackemslashem]

I noticed that warning symbols (1,2,3,4,5) don't appear when steam clouds from steam vortices or poison gas clouds from hezrou or the plane of fire are present. This seems a bit inconsistent with the general behavior of warning since it works through walls and when the player is blind. Warning also seems to work through the clouds on the plane of air.