configure: Split adding of CFLAGS and CPPFLAGS for hardened toolchain
Merge commit '2d589273dd36c5eb271a035ea0e669b64dae257f'

* commit '2d589273dd36c5eb271a035ea0e669b64dae257f':
  configure: Split adding of CFLAGS and CPPFLAGS for hardened toolchain

Merged-by: Michael Niedermayer <michaelni@gmx.at>
doc/examples/transcoding: use av_packet_rescale_ts()

Simplify.
lavf/hls: add hls_ts_option

Same as COMMITID 4f5493fe2380ad4aba67759baa7d7d4437f2e776.

Signed-off-by: Stefano Sabatini <stefasab@gmail.com>
avformat/flacenc: use av_clip() instead of av_clip_c()
sws: use av_clip() instead of av_clip_c()