Provide a runtime mechanism to set the IPv6 suffixes for reverse lookups.
Provide a runtime mechanism to disable each of the IPv6 reverse lookup
methods.
Provide a mechanism to free memory allocated by res_{n}init().
--with-irs-gr=yes #define WANT_IRS_GR --with-irs-nis=yes #define WANT_IRS_NIS --with-irs-pw=yes #define WANT_IRS_PW