session: Free session->kbdint in ssh_free()

Makes sure we free pending keyboard auth prompts
so prompts that have not be replied to do not leak.

Signed-off-by: Peter Volpe <pvolpe@redhat.com>
Reviewed-by: Andreas Schneider <asn@cryptomilk.org>
(cherry picked from commit 76ba2b0055)

src/session.c

@@ -257,6 +257,10 @@ void ssh_free(ssh_session session) {
       ssh_list_free(session->ssh_message_list);
   }
 
+  if (session->kbdint != NULL) {
+    ssh_kbdint_free(session->kbdint);
+  }
+
   if (session->packet_callbacks) {
     ssh_list_free(session->packet_callbacks);
   }