configure: Use the right variables in check_host_cpp

HOSTCPPFLAGS and HOSTCFLAGS are only set in config.mak.

Signed-off-by: Martin Storsjö <martin@martin.st>
rtpenc_chain: Pass the initial time_base hint on to the chained muxer

In practice this hint is ignored - the rtp muxer always overwrites
the stream time base without taking the hint into account. But as
a general practice this is the correct way to pass a time base hint
on to a chained muxer.

This avoids warnings about using the codec time base as hint
being deprecated.

Signed-off-by: Martin Storsjö <martin@martin.st>
Merge commit '3f2c70355ab722bc9f741bd3ed8224c7cfb62379'

* commit '3f2c70355ab722bc9f741bd3ed8224c7cfb62379':
  configure: Use the right variables in check_host_cpp

See: 453944cc77b9ea27c74011eb7c0e20c887b321cf
Merged-by: Michael Niedermayer <michaelni@gmx.at>
Merge commit '2bb2c2bd75e5f4b28a945511cda77e0a1a44c758'

* commit '2bb2c2bd75e5f4b28a945511cda77e0a1a44c758':
  rtpenc_chain: Pass the initial time_base hint on to the chained muxer

See: [FFmpeg-devel] [PATCH] avformat/rtpenc_chain: Set timebase
Merged-by: Michael Niedermayer <michaelni@gmx.at>