aspect: don't scale to fullscreen by <101%
Don't crash with Libav 11
Merge branches 'autoexpand' and 'libav' into all
Fix libdvdread and libdvdnav detection

Use pkg-config to detect both.

Since libdvdnavmini no longer exists, permit only
internal libdvdnav to be used with internal libdvdread.
Fix building with libdvdnav 4.2.1
Merge branch 'libdvdnav' into all