If you stuck around for the Black Panther end-credits scene you saw Captain America's old war-buddy-turned-frenemy, Bucky Barnes, emerge from that hut in Wakanda. So what's the deal?
The kids in Wakanda call Bucky "The White Wolf." In the comics T'Chaka adopted a white child named hunter, a kid whose parents died in a plane crash in Wakanda. Hunter grew up to be a true patriot of the reclusive kingdom, though one who was often at odds with his adopted brother, T'challa.
Taking on the alias of white wolf, hunter has been leader of the Wakandan secret police, a mercenary, and above all, a true lover of his adopted homeland. Clearly, Bucky Barnes isn't this character specifically, though the films have often utilized amalgams of different characters and storylines.
Most likely, this "White Wolf" reference in Black Panther was a nod to comic fans: Bucky is, after all, a white dude who was more or less "adopted" by Wakanda and as we've seen in the Infinity War spots, a man who will defend the kingdom.