incRefcount
Increment the availability of index for peerId (a HAVE message). Mirrors piece_picker::inc_refcount(piece_index_t, torrent_peer const*). The peer token is unused here (libtorrent only uses it for debug refcount sets) but kept in the signature for symmetry with the bitfield overload.
Increment availability for every piece in bitmask for peerId (a BITFIELD message). If the bitmask covers every piece it is treated as a seed and routed through incRefcountAll. Mirrors the bitfield inc_refcount.