Intellisense not working for system libraries on native env

I have a project which I want to build in native env on Os X. Some system libraries are not found by intellisense. They are installed on my machine, if I build using the default VSCode build system instead of platformio, there are no problems with intellisense.

The following libraries are detected no problem by intellisense:
#include <stdint.h>
#include <stdio.h>
#include <string.h>

However, it does not find these two for example:
#include <sys/socket.h>
#include <netinet/in.h>

Would you be so kind to give me a clue as to what’s happening?