storage: reject unknown flags

storage: reject unknown flags

* src/storage/storage_backend.c (virStorageBackendCreateBlockFrom)
(virStorageBackendCreateQemuImg)
(virStorageBackendCreateQcowCreate): Reject unknown flags.
* src/storage/storage_backend_disk.c (virStorageBackendDiskBuildPool)
(virStorageBackendDiskDeleteVol): Likewise.
* src/storage/storage_backend_fs.c
(virStorageBackendFileSystemNetFindPoolSources)
(virStorageBackendFileSystemBuild)
(virStorageBackendFileSystemDelete, createFileDir)
(virStorageBackendFileSystemVolBuildFrom)
(virStorageBackendFileSystemVolDelete): Likewise.
* src/storage/storage_backend_iscsi.c
(virStorageBackendISCSIFindPoolSources): Likewise.
* src/storage/storage_backend_logical.c
(virStorageBackendLogicalFindPoolSources)
(virStorageBackendLogicalBuildPool)
(virStorageBackendLogicalDeletePool)
(virStorageBackendLogicalDeleteVol): Likewise.
* src/storage/storage_driver.c (storageOpen, storagePoolCreate)
(storagePoolDefine, storagePoolRefresh, storagePoolGetXMLDesc)
(storageVolumeCreateXML, storageVolumeCreateXMLFrom)
(storageVolumeGetXMLDesc): Likewise.