u3: cleans up xtract.c (mostly style, minor refactoring)
u3: cleans up xtract.c (mostly style, minor refactoring)

urbit/urbit,jfranklin9000/urbit,urbit/urbit,urbit/urbit,urbit/urbit,urbit/urbit,ngzax/urbit,urbit/urbit,urbit/urbit,ngzax/urbit,jfranklin9000/urbit,jfranklin9000/urbit,ngzax/urbit,jfranklin9000/urbit,ngzax/urbit,jfranklin9000/urbit,jfranklin9000/urbit,ngzax/urbit,ngzax/urbit,ngzax/urbit,jfranklin9000/urbit