fix for #H229

fix for #H229

<Someone> wrote:
>>comments:
>>When you commit suicide with a potion of oil (lit), sometimes nethack
>>reports an `obj_is_local' error just after disclosing all the game
>>variables. This has been found in-game (don't ask) and reproduced in
>>wizard mode and in-game (start-scumming).
>
> 0) a neutral human wizard (the scrolls/spellbooks burning, potions boiling ;))
> 1) wish up 3 potions of oil (so that the 2 remaining will definitely kill you)
> 2) a'pply one of them
> 3) stand 1 square away from a wall, like "| @"
> 4) throw the lit potion into the wall (`h' in this case)
> 5) answer `yes' on all prompts.

The thrown potion of oil, which was extracted from any chain
during the throw, still had its timers attached when the call to
splatter_burning_oil() was made. If that killed the hero, a
panic would result during bones file creation (saving timers)
because (obj->where == OBJ_FREE) on the potion.

Remove the timer prior to splattering the oil inside.