This PR optimizes out isFused and crossPageIPFFix usages in Rob's DispatchData. They will not be stored in ROB. Now DispatchData has only 38 bits.

* isFused is merged with commitType (2 bits reduced)
* crossPageIPFFix is used only in ExceptionGen (1 bit reduced)
* rename: reduce ldest usages
* decode: set isMove to false if ldest is zero