fix 81699266df94790374668e66ea6fd80b249fea88

why code compiled multiple times with this error and than suddenly compiler noticed problem is beyond me
move to functions to a better file
polymorph_player_instead_stoning()

replaces (poly_when_stoned(youmonst.data) && polymon(PM_STONE_GOLEM)) - shorter, allows more than one polymorphing instead stoning (without this poly_when_stoned should be called poly_to_ston_golem_when_stoned)
force possible transformation on stoning

on stoning force transformation to viable polymorph form, even if target was genocided (changes death to self-genocide instead of stoning)

it is theorethical as only ungenocidable stone golems are currently viable targets
special golem stoning is now coded in a one place