zfeature_is_supported
if (zfeature_is_supported(feature.fi_guid))
if (zfeature_is_supported(feature.fi_guid)) {
extern boolean_t zfeature_is_supported(const char *);
if (zfeature_is_supported(nvpair_name(nvp)))
if (!zfeature_is_supported(nvpair_name(nvp))) {
!zfeature_is_supported(za.za_name)) {