fix ++hmac to work on >64 bit keys
fix ++hmac to work on >64 bit keys

Reload: zuse, vanes

A  swap 3  was being performed which should not have been. Still not confident inthe endianness of the code as a whole, but seems to work for test values.

ngzax/urbit,jfranklin9000/urbit,jfranklin9000/urbit,ngzax/urbit,belisarius222/arvo,jfranklin9000/urbit,urbit/urbit,joemfb/arvo,jfranklin9000/urbit,belisarius222/arvo,solri/arvo,jfranklin9000/urbit,ohAitch/arvo,Fang-/arvo,urbit/urbit,urbit/urbit,ngzax/urbit,ngzax/urbit,urbit/urbit,ohAitch/arvo,eglaysher/arvo,urbit/urbit,urbit/urbit,jfranklin9000/urbit,urbit/urbit,joemfb/arvo,jfranklin9000/urbit,cgyarvin/arvo,cgyarvin/arvo,ngzax/urbit,ngzax/urbit,ngzax/urbit