Bug fixed.

Fix the bugs in FlushToMem functions.

source/tensor/XTensor.cpp

@@ -1933,7 +1933,10 @@ void XTensor::FlushToMem(XMem* targetMem)
         else if (mem != targetMem) {
             void* tmpData = targetMem->Alloc(targetMem->devID, GetDataSizeInChar());
             XMemCopy(tmpData, targetMem->devID, data, devID, GetDataSizeInChar());
-            mem->Release(data, GetDataSizeInChar(), signature);
+            if (mem != NULL)
+                mem->Release(data, GetDataSizeInChar(), signature);
+            else
+                XMemFree(devID, data);
             data = tmpData;
             mem = targetMem;
             devID = mem->devID;