fix #H6610 - completely burnt paper golem

fix #H6610 - completely burnt paper golem

When a monster killed a paper golem with a fire attack, the player was
told that the golem "burns completely" yet it might still leave some
blank scrolls as 'corpse'.  The fix for that was one-line, but several
other death-by-fire situations which didn't report "burns completely"
were also leaving scrolls:  fireball spell or scroll of fire or other
fire explosions (if any), also wand of fire.  Fire trap and poly'd
hero with fire attack were already suppressing 'corpse'.