Very useful patch but the naming is not correct, . and .. or not your typical hidden type, autoindex_show_dot_folders would make more sense.

And "if (ngx_de_name(&dir)[0] == '.') {" will exclude files which start with a dot,

if (ngx_de_name(&dir) == '.') or (ngx_de_name(&dir) == '..') {, would be better IMHO.