At some point, MPlayer forked their own libdvdnav and many other libraries. MPlayer continues to compile with many stock libraries, but starting about two weeks ago, MPlayer no longer compiles with stock libdvdnav. It was related to
this svn commit in April, and nicodvb finally decided
it's okay to assume MPlayer is using its own fork. I don't know if the plan is to eventually link libdvdnav2 directory to their build tree at some point, like what they do with libdvdcss and libav{codec,format,util}, but this is where to find libdvdnav2 that works:
svn co svn://svn.mplayerhq.hu/dvdnav/trunk/libdvdnav2
For my own information, this is where to find mplayer build tree:
svn co svn://svn.mplayerhq.hu/mplayer/trunk mplayer
Make and install libdvdnav2, then make clean and reconfigure mplayer. It should work.
Update: it seems that they now prefer
svn co svn://svn.mplayerhq.hu/dvdnav/trunk/libdvdnav (not libdvdnav2) once again.
