Building cURL: file descriptor issues

I am playing around with WASM and namely with the [wasm3](https://github.com/wasm3/wasm3) project. It accepts modules compiled with `-s WASM=1 -s SIDE_MODULE=1` which is quite neat.

So to play around with this, I built mbedTLS with Emscripten successfuly which is quite neat in and on itself! However, when then building CMake, I do get a successful build, but also this:

```
PS C:\Users\ingwi\work\curl\build.wasm> node .\src\curl.js -v http://192.168.0.1
* Trying 192.168.0.1:80...
* Could not set TCP_NODELAY: Protocol not available
* Failed to set SO_KEEPALIVE on fd 3
* Immediate connect fail for 192.168.0.1: Host is unreachable
* Closing connection 0
curl: (7) Couldn't connect to server
```

Interesting. This IP is the one of my local access point, so it should most definitively exist. Also, domain name resolution also does not work. Something tells me this is something `emcmake` did not cover for me already.

So, what `emcc` flags do I have to use to get this working? I am quite positive the issue is not in cURL itself but rather the `CFLAGS` I have to give it. Currently, I use `-s ASSERTIONS=0` to remove the `sigaction()` messages. (I got an astounding amount of those...).