examples: Update ssh_server_fork for new SSH_BIND_OPTIONS_HOSTKEY
examples: Update ssh_server_fork for new SSH_BIND_OPTIONS_HOSTKEY

Tested by

ssh_server_fork -k <an ecdsa key> -k <an rsa key> ...

and connection succeeded with OpenSSH clients both for ECDSA and RSA
(the latter forced via -o HostKeyAlgorithms=ssh-rsa and some known
hosts clearing was necessary).  Also

ssh_server_fork -k <an ecdsa key> -k <another ecdsa key> ...

caused the second key to be used, as expected.

Signed-off-by: Alan Dunn <90d3ad16cd4565f91305ac667132a38a0361079b@gmail.com>
Reviewed-by: Andreas Schneider <5be00ddc76278cf6077f5047ca3384a88460c671@cryptomilk.org>

taikoo/libssh,nviennot/libssh,Distrotech/libssh,kedazo/libssh,robxu9/libssh,DouglasHeriot/libssh,mwgoldsmith/ssh,nviennot/libssh,sebadoom/libssh,wangshawn/libssh,kedazo/libssh,mwgoldsmith/ssh,robxu9/libssh,robxu9/libssh,mwgoldsmith/libssh,mwgoldsmith/libssh,kedazo/libssh,taikoo/libssh,taikoo/libssh,pouete/libssh,wangshawn/libssh,robxu9/libssh,Distrotech/libssh,Distrotech/libssh,nviennot/libssh,mwgoldsmith/ssh,pouete/libssh,pouete/libssh,sebadoom/libssh,sebadoom/libssh,DouglasHeriot/libssh,sebadoom/libssh,mwgoldsmith/ssh,elastichosts/libssh,nviennot/libssh,Distrotech/libssh,DouglasHeriot/libssh,pouete/libssh,DouglasHeriot/libssh,mwgoldsmith/libssh,wangshawn/libssh,elastichosts/libssh,taikoo/libssh,wangshawn/libssh,elastichosts/libssh,kedazo/libssh,mwgoldsmith/libssh