Nullterminate strings returned via sysctl.

PR:		195668

sys/dev/cxgbe/t4_l2t.c

@@ -321,6 +321,7 @@ sysctl_l2t(SYSCTL_HANDLER_ARGS)
 		mtx_unlock(&e->lock);
 	}
 
+	sbuf_putc(&sb, 0); /* nullterm */
 	rc = sbuf_finish(sb);
 	sbuf_delete(sb);
 

sys/dev/cxgbe/t4_main.c

@@ -5090,6 +5090,7 @@ sysctl_int_array(SYSCTL_HANDLER_ARGS)
 	for (i = arg1; arg2; arg2 -= sizeof(int), i++)
 		sbuf_printf(&sb, "%d ", *i);
 	sbuf_trim(&sb);
+	sbuf_putc(&sb, 0); /* nullterm */
 	sbuf_finish(&sb);
 	rc = sysctl_handle_string(oidp, sbuf_data(&sb), sbuf_len(&sb), req);
 	sbuf_delete(&sb);