Fix a few memory leaks.

Patch due to Chris Staite.

(cherry picked from commit 78989c97c9)

ssh.c

@@ -9458,6 +9458,8 @@ static void do_ssh2_authconn(Ssh ssh, unsigned char *in, int inlen,
                     logevent("Sent public key signature");
 		    s->type = AUTH_TYPE_PUBLICKEY;
 		    key->alg->freekey(key->data);
+                    sfree(key->comment);
+                    sfree(key);
 		}
 
 #ifndef NO_GSSAPI