R788 - bones corpses shouldn't all be human

R788 - bones corpses shouldn't all be human
u.umonnum was used to create the corpse in a bones file.  However, unless
you're polymorphed and manage to actually die in that form, u.umonnum
refers to a role monster, which all have M2_HUMAN set, so they're all
human.  Even if the role monsters were mutated dynamically when the game
starts, the problem would still exist, just in a different form.
Use urace to determine the corpse type instead.