virsh: prefer unsigned flags

virsh: prefer unsigned flags

virsh had some leftover 'int flags', and even an 'int flag'
declaration, compared to our preferred style of 'unsigned int flags'.

* tools/virsh.c (cmdUndefine, cmdSave, cmdSaveImageDumpxml)
(cmdSaveImageEdit, cmdManagedSave, cmdRestore, cmdDump)
(cmdVcpuPin, cmdSetvcpus, cmdSetmem, cmdSetmaxmem, cmdDumpXML)
(cmdDomXMLFromNative, cmdDomXMLToNative, doMigrate)
(cmdInterfaceEdit, cmdInterfaceDumpXML, cmdEdit): Match coding
style for flags.
(struct vshComdOptDef): Rename field member.
(vshCmddefOptParse, vshCmddefHelp): Adjust clients.