native get_user_attacker(index, ...);
If provided, the attacker weapon will be stored in an
optional second parameter, and the body hit place will be
stored in an optional third parameter
Returns the last known attacker of a client.
As of AMXX 1.75 this can return a non-client entity index if the client
was attacked by a non-client entity.
Attacker client index, a non-client entity or 0 if no
attacker was found
If the client index is not within the range of 1 to
MaxClients, an error will be thrown.