avcodec/libvorbisenc: Give CODEC_CAP_SMALL_LAST_FRAME to libvorbis encoder.

The libvorbis encoder already supports a small last frame, but the layer
above doesn't know that because we didn't register the small last frame
capability.
Signed-off-by: Michael Niedermayer <michaelni@gmx.at>

libavcodec/libvorbisenc.c

@@ -372,7 +372,7 @@ AVCodec ff_libvorbis_encoder = {
     .init           = libvorbis_encode_init,
     .encode2        = libvorbis_encode_frame,
     .close          = libvorbis_encode_close,
-    .capabilities   = CODEC_CAP_DELAY,
+    .capabilities   = CODEC_CAP_DELAY | CODEC_CAP_SMALL_LAST_FRAME,
     .sample_fmts    = (const enum AVSampleFormat[]) { AV_SAMPLE_FMT_FLTP,
                                                       AV_SAMPLE_FMT_NONE },
     .priv_class     = &vorbis_class,