Investigate missing export * exports

[dcodeIO]

While working on #1129 I noticed that some module exports are missing both in the binary and in the corresponding generated definition file. In particular:

import * as util from "./util/index";
export { util };

in index.ts yields exactly one export util.isPowerOf2, but misses the star re-exports in util/index.ts. If I'm not mistaken this is not limited to module exports, but also happens if one tries to

import * as wasi from "bindings/wasi";

which also has a star re-export

export * from "./wasi_snapshot_preview1";

Pinning here so we don't forget.