George Kadianakis authored Aug 04, 2017 and Nick Mathewson committed Aug 08, 2017

We used to do:
   h = H(BLIND_STRING | H(A | s | B | N )
when we should be doing:
   h = H(BLIND_STRING | A | s | B | N)

Change the logic so that hs_common.c does the hashing, and our ed25519
libraries just receive the hashed parameter ready-made. That's easier
than doing the hashing on the ed25519 libraries, since that means we
would have to pass them a variable-length param (depending on whether
's' is set or not).

Also fix the ed25519 test vectors since they were also double hashing.