Clears the text on a synchronized HUD channel.
This is not the same as sending "" because it guarantees that it won't overwrite text on another channel. For example, consider the scenario:
1. Your synchronized message goes to channel 3. 2. Someone else's non-synchronized message goes to channel 3.
If you were to simply send "" on your synchronized message, then someone else's text could be overwritten.
void ClearSyncHud(int client, Handle sync)
Client index to send the message to.
Client not in-game, or sync object not valid.