What changed for proxying between 2.0.8 and 2.0.23?

Hi, in emsdk 2.0.8 my emcc args inlcuded:
```
-s USE_PTHREADS=1
-s PROXY_TO_PTHREAD=1
-s MODULARIZE=1
-s EXPORTED_FUNCTIONS="[_main, _proxy_main]"
```

followed by javascript:

```
core.ccall('proxy_main', ...);
```

however building with 2.0.23 it complains `emcc: error: undefined exported symbol: "_proxy_main" [-Wundefined] [-Werror]`

I can remove the `_proxy_main` from the list, but then how to run main proxied?