struct dvd_struct

[Peter Seebach]

Not sure whose bug this is, but libdvdcss won't compile on NetBSD, because
"dvd_struct" is actually a union on current BSD.  If I just change it to
"dvd_struct dvd", I run into a few other problems, but that helps some.

Hmm.  It looks like NetBSD renamed "dvd.format" to "dvd.type".  More
generally, it looks like NetBSD now has "LINUX_DVD_STRUCT"; if I define that,
it compiles just fine.  So, you may need a test to distinguish between
BSD_DVD_STRUCT and LINUX_DVD_STRUCT in <sys/dvdio.h>.

-s