iohelper: skip lseek() and ftruncate() on block devices
iohelper: skip lseek() and ftruncate() on block devices

Signed-off-by: Simon Rowe <6b0999b796d5e18833f96f31b20ec46c7a765474@nutanix.com>
Signed-off-by: Michal Privoznik <83d82aaba2eed257f4814b0c239c260c4caaadf0@redhat.com>
Reviewed-by: Michal Privoznik <83d82aaba2eed257f4814b0c239c260c4caaadf0@redhat.com>

nertpinx/libvirt,jfehlig/libvirt,jfehlig/libvirt,crobinso/libvirt,nertpinx/libvirt,libvirt/libvirt,olafhering/libvirt,olafhering/libvirt,zippy2/libvirt,nertpinx/libvirt,zippy2/libvirt,olafhering/libvirt,jfehlig/libvirt,jfehlig/libvirt,nertpinx/libvirt,nertpinx/libvirt,crobinso/libvirt,zippy2/libvirt,libvirt/libvirt,libvirt/libvirt,crobinso/libvirt,libvirt/libvirt,zippy2/libvirt,olafhering/libvirt,crobinso/libvirt