Do proper fallback on BUP on corrupted IFO
ref: DIE WELLE
Truncated IFO on main title prevents playback, as we have no proper fallback outside of the case of missing file.
We need to store fallback status for later accesses as later code paths will not trigger checks when opening files.
libdvdnav: DVD Title: DVDVolume
libdvdnav: DVD Serial Number: 39128054
libdvdnav: DVD Title (Alternative): DVDVolume
-r-xr-xr-x. 1 fcartegn fcartegn 75776 18 août 2008 VTS_01_0.BUP
-r-xr-xr-x. 1 fcartegn fcartegn 28672 18 août 2008 VTS_01_0.IFO