[PetraAI] - Only try to subtract resource gift from "waitingfortribute" if gift contains required resource.
Check for existance of requested type in event message, since rP23065 stoped sending resource codes with 0 tribute and that was not even guaranteed to get before through another options how to trigger tribute event.
Differential Revision: https://code.wildfiregames.com/D2703
Patch by: Freagarach
Reviewed by: Angen
Comments by: elexis