dh: Move ssh_get_hexa() and ssh_print_hexa() down.
dh: Move ssh_get_hexa() and ssh_print_hexa() down.

This way they are in the documentation block for the session and we get
documentation for them.

mwgoldsmith/ssh,mwgoldsmith/ssh,mwgoldsmith/ssh,mwgoldsmith/ssh,mwgoldsmith/libssh,mwgoldsmith/libssh,mwgoldsmith/libssh,mwgoldsmith/libssh