`gnrc_netif_hdr_build()` calls internally `gnrc_netif_hdr_init()`, which does initialize `gnrc_netif_hdr_t::rssi` and `gnrc_netif_hdr_t::lqi`. So no need to do this twice.
`gnrc_netif_hdr_build()` calls internally `gnrc_netif_hdr_init()`, which does initialize `gnrc_netif_hdr_t::rssi` and `gnrc_netif_hdr_t::lqi`. So no need to do this twice.