[DllAvUtil] Plumb in missing av_samples_fill_arrays and av_samples_copy
[rbp/omxplayer] Stop using AVCODEC_MAX_AUDIO_FRAME_SIZE

This constant has been deprecated and is now gone in FFmpeg 2.0.

See #3006

Also made use of av_samples_fill_arrays and av_samples_copy
and have simplified the code.
Merge pull request #3022 from popcornmix/avoid_avcodec_max

[rbp/omxplayer] Stop using AVCODEC_MAX_AUDIO_FRAME_SIZE