Fix ioctl recording of multiple device open/close cycles.

This regressed in 0.6 to only keep the data of the last cycle.
ioctl_record_open() was seeking to the end of the .ioctl file if it already
existed, so that ioctl_tree_read() had nothing to read and thus the existing
data was discarded.
Update canon-powershot-sx200.ioctl for libgphoto 2.5.4