This is a separate program and is used mainly with hostapd, so it is better to move this into the hostapd subdirectory now that Milenage code has already been moved into src/crypto. Milenage was the only generic component in hlr_auc_gw.
The Test Set 19 from TS 35.208 has an AMF with the separation bit set and as such, it is suitable for EAP-AKA' testing.