The implementation clears the context / state data from memory when it
is finished with it.  Prior to this commit, however, it was actually
only clearing the first 4 bytes on x86 or 8 bytes on x86_64.

clang warns:

  warning: argument to 'sizeof' in 'memset' call is the same
  expression as the destination; did you mean to dereference it?
      [-Wsizeof-pointer-memaccess]