h264_mp4toannexb_bsf: K&R formatting cosmetics
h264_mp4toannexb_bsf: factor out extradata parsing
h264_mp4toannexb_bsf: return a padded buffer

The code using the returned buffer might expect it to be
FF_INPUT_BUFFER_PADDING_SIZE padded as any other avpacket.
bitstream: K&R formatting cosmetics
bitstream: forward error values and drop few abort()
avf: split off format register and lookup function
avf: move ff_http_match_no_proxy to network

It is only used by network protocols.
avf: move riff tags accessors where they belong
avf: move ff_write_chained to mux.c
avf: move url utility functions in a separate file
utils: fix avcodec_flush_buffers pre-reference counting compatibility

The to_free AVframe must be freed just like the other ones.
Indeed, the calling application may expect all frames to be
released.

(This regression caused use-after-free in VLC with hwaccel.)

Signed-off-by: Rémi Denis-Courmont <remi@remlab.net>

Signed-off-by: Luca Barbato <lu_zero@gentoo.org>