On linux you proably have to install loads of crap.
sudo apt-get install libcurl-dev
Like I said on Windows is where people were having problems getting the curl headers, and I don't know where you got them from because they are not in the MinGW folder.
We can let it die.
It's fine I already have it started and that will be the last of the remaining old Game Maker API to implement.
Of course implementing the new GM:S networking functions should be more important.
Here is what is left to do...
1) Make buffers be able to read/write floats right now if you write 214.568 it comes back out as 214 with the point precision dropped off.
2) Implement buffer data alignment
3) Merge networking functions together, I don't think we need two sets, I think I can expand Studio's so that there exists only one set, I haven't decided yet.
4) Implement network_receive(); which decodes a buffer into a data structure map, or else just implement that asynchronous network event and make a global constant for it.
5) Make network_ functions non-blocking.