lavf: default .ogg audio to libvorbis if we can

Since 2007, the Xiph.org Foundation recommends that .ogg only be used
for Ogg Vorbis audio files.

Source: http://wiki.xiph.org/index.php/MIME_Types_and_File_Extensions

However we only do it if we have libvorbis available because the
built in vorbis encoder is not as good.

Signed-off-by: Vittorio Giovara <vittorio.giovara@gmail.com>
dnxhddec: return proper error code

Signed-off-by: Vittorio Giovara <vittorio.giovara@gmail.com>
arm: Remove a stray .fpu directive

Signed-off-by: Vittorio Giovara <vittorio.giovara@gmail.com>