libzutil: import: fix unused, remove argsused

Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Signed-off-by: Ahelenia Ziemiańska <nabijaczleweli@nabijaczleweli.xyz>
Closes #12844

lib/libzutil/zutil_import.c

@@ -1393,6 +1393,7 @@ static nvlist_t *
 zpool_find_import_impl(libpc_handle_t *hdl, importargs_t *iarg,
     pthread_mutex_t *lock, avl_tree_t *cache)
 {
+	(void) lock;
 	nvlist_t *ret = NULL;
 	pool_list_t pools = { 0 };
 	pool_entry_t *pe, *penext;