include/sys/socket.h: ensure SOMAXCONN symbol is defined
include/sys/socket.h: ensure SOMAXCONN symbol is defined

SOMAXCONN is expected to be defined in this header, but for the esp32
port is found in net/if.h from newlib.

Avoid the issue by including the net/if.h header in sys/socket.h so that
compatibility is preserved.

Signed-off-by: Francesco Giancane <francesco.giancane@accenture.com>

Merges https://github.com/espressif/esp-idf/pull/4637

espressif/esp-idf,espressif/esp-idf,espressif/esp-idf,espressif/esp-idf