o Minor bugfixes (hidden service):
    - When encoding a legacy ESTABLISH_INTRO cell, we were using the sizeof()
      on a pointer instead of real size of the destination buffer leading to
      an overflow passing an enormous value to the signing digest function.
      Fortunately, that value was only used to make sure the destination
      buffer length was big enough for the key size and in this case it was.
      Fixes bug 21553; bugfix on tor-0.3.0.1-alpha.