How to USE_KECCAK functions?

[tomasz90]

Hi!

I just created repo based on your library. I am trying to generate ethereum addresses and pk based on mnemonic and derivation path. This concept works, but I met such issue - I tried to use function keccak_256, but this is restricted by macro USE_KECCAK.
I tried many combination of setting USE_KECCAK 1 in cpp file, header file, before imports etc.. none worked. The only one solution, but rather workaround was setting build_flags = -D USE_KECCAK=1 in platformio.ini file. Do you know how to handle this?