In unix/native/libnet/Inet4AddressImpl.c there exist two paths of code for
Java_java_net_Inet4AddressImpl_getLocalHostName
Java_java_net_Inet4AddressImpl_lookupAllHostAddr and
Java_java_net_Inet4AddressImpl_getHostByAddr

There exists a code path that is used for _ALLBSD_SOURCE when the C-Runtime does not have gethostby... functions which seems a quite rare case. And it's even more obsolete as this code path is rather identical to the main path and implements lookup operations based on getaddrinfo/getnameinfo just as its counterparts.