Fix bug in eltorito.
Fix bug in eltorito.

When we are doing eltorito and have SVDs, we only
want to set the directory record during the PVD
parse, not the SVD parse.  This is so that later
thing will all work appropriately.

Signed-off-by: Chris Lalancette <281cd07d7578d97c83271fbbf2faddb83ab3791c@gmail.com>

clalancette/pycdlib,clalancette/pyiso