This way they can be reused by other code without including the whole
decoder-specific hevcdec.h
Also, add the HEVC_ prefix to them, since similarly named values exist
for H.264 as well and are sometimes used in the same code.

This is more consistent with the rest of libav and frees up the hevc.h
name for decoder-independent shared declarations.

Deprecate the current bitstream filtering API.

*poutbuf is non-const, so this casts it explicitly.
This suppresses -Wdiscarded-qualifiers seen in e.g
http://fate.ffmpeg.org/log.cgi?time=20150919100330&log=compile&slot=x86_64-archlinux-gcc-enableshared.
Signed-off-by: Ganesh Ajjanagadde <gajjanagadde@gmail.com>
Signed-off-by: Michael Niedermayer <michael@niedermayer.cc>

Signed-off-by: Michael Niedermayer <michael@niedermayer.cc>

libavcodec/hevc_mp4toannexb_bsf.c: Optional argument "private_spspps_buf" to avoid extradata modification.
Signed-off-by: Michael Niedermayer <michael@niedermayer.cc>

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