netscope.c:23:50: error: unused parameter 'addr' when HAVE_IF_NAMETOINDEX undefined on illumos

On OpenIndiana 2020.04 (an illumos distribution) compilation of BIND main commit 78a4ed31 fails in lib/isc/netscope.c with:

netscope.c: In function 'isc_netscope_pton':
netscope.c:23:50: error: unused parameter 'addr' [-Werror=unused-parameter]
 isc_netscope_pton(int af, char *scopename, void *addr, uint32_t *zoneid) {
                                                  ^~~~
cc1: all warnings being treated as errors

It seems that addr is used only when HAVE_IF_NAMETOINDEX is defined.