Mark 'addr' as unused if HAVE_IF_NAMETOINDEX is not defined
requested to merge 1994-netscope-c-23-50-error-unused-parameter-addr-when-have_if_nametoindex-undefined-on-illumos-v9_11 into v9_11
Also 'zone' should be initialised to zero.
(cherry picked from commit e7662c4c)
Closes #1994 (closed)