Remove unsigned message pointer from Runtime

chain/vm/runtime.go

@@ -34,7 +34,6 @@ type Runtime struct {
 
 	vm        *VM
 	state     *state.StateTree
-	msg       *types.Message
 	vmsg      vmr.Message
 	height    abi.ChainEpoch
 	cst       cbor.IpldStore

chain/vm/vm.go

@@ -97,7 +97,6 @@ func (vm *VM) makeRuntime(ctx context.Context, msg *types.Message, origin addres
 		ctx:         ctx,
 		vm:          vm,
 		state:       vm.cstate,
-		msg:         msg,
 		origin:      origin,
 		originNonce: originNonce,
 		height:      vm.blockHeight,