Fixed: rows on the scoreboard would be drawn incorrectly on the intermission screen after a player spectated or left the game.

If a player spectated or left the game while on the intermission, some rows on the scoreboard would get messed up (e.g. spectator rows would be mixed with in-game player rows instead of separated, empty rows are left on the scoreboard, the same team's header gets drawn multiple times, etc.).

This was because the scoreboard code relied on the in-game and spectator player counts found in st_hud.cpp, but these along with the HUD didn't update during intermissions because the HUD isn't used there. As such, the player counts are now updated in a separate function: HUD_RefreshPlayerCounts, which the scoreboard can call when it refreshes during an intermission.