packet: Fix timeout on hostkey type mismatch instead of proper error

If the hostkey type was not in the list of acceptable hostkey
types, the function failed to set the error state. Due to the
fact that the calling function ssh_packet_process() does not
handle the SSH_ERROR return code, the newkeys packet from the
server was silently ignored, stalling the connection until a
timeout occurred.

Signed-off-by: Tilo Eckert <tilo.eckert@flam.de>
Reviewed-by: Andreas Schneider <asn@cryptomilk.org>
(cherry picked from commit 4b6eb05023)

src/packet_cb.c

@@ -198,7 +198,7 @@ SSH_PACKET_CALLBACK(ssh_packet_newkeys){
                           "preference (%s)",
                           server_key->type_c,
                           session->opts.wanted_methods[SSH_HOSTKEYS]);
-            return -1;
+            goto error;
         }
     }