dnvlist_take_binary
actual_val = dnvlist_take_binary(nvl, key, &actual_size, default_val,
actual_val = dnvlist_take_binary(nvl, "123", &actual_size, default_val,
actual_val = dnvlist_take_binary(nvl, "otherkey", &actual_size,
void *dnvlist_take_binary(nvlist_t *nvl, const char *name, size_t *sizep, void *defval, size_t defsize);