I don’t have my custom build here, so can’t check. But the idea is that you can define
WLED_ANALOG_LEDS_INVERT
in there, just like you define other configuration options.
Have you been able to build wled for your configuration already? If so, that flow should have told you to create this platform_overfide.ini file. Or if you didn’t create such, you use a standard configuration in platform.ini - you could just modify that one as well.
Alternatively, just define it in the header file directly, or remove the #ifdef. That’s only there to make it more generic, but it wasn’t picked up by any developer unfortunately…