Our copy functions format and parse XML thus are not able to copy data.
Annotate the private data pointers that this is happening.
struct _virDomainXMLPrivateDataCallbacks {
virDomainXMLPrivateDataAllocFunc alloc;
virDomainXMLPrivateDataFreeFunc free;
+ /* note that private data for devices are not copied when using
+ * virDomainDefCopy and similar functions */
virDomainXMLPrivateDataNewFunc diskNew;
virDomainXMLPrivateDataNewFunc hostdevNew;
virDomainXMLPrivateDataFormatFunc format;