Re: [libvirt] [PATCH 05/16] snapshot: Drop virDomainSnapshotDef.current

The only use for the 'current' member of virDomainSnapshotDef was with the PARSE/FORMAT_INTERNAL flag for controlling an internal-use <active> element marking whether a particular snapshot definition was current, and even then, only by the qemu driver on output, and by qemu and test driver on input. But this duplicates vm->snapshot_current, and gets in the way of potential simplifications to have qemu store a single file for all snapshots rather than one file per snapshot. Get rid of the member by adding a bool* parameter during parse (ignored if the PARSE_INTERNAL flag is not set), and by adding a new flag during format (if FORMAT_INTERNAL is set, the value printed in <active> depends on the new FORMAT_CURRENT). Then update the qemu driver accordingly.