Revert "rtpenc_chain: Don't copy the time_base back to the caller"

While it strictly isn't necessary to copy the time base (since
any use of it is scaled in ff_write_chained), it still is better
to signal the actual time base to the caller, avoiding one
unnecessary rescaling. This also lets the caller know what the
actual internal time base is, in case that is useful info
for some caller.

This reverts commit 397ffde115f4e0482a007b672f40457596cebfc4.

Signed-off-by: Martin Storsjö <martin@martin.st>
ppc: Fix compilation for ppc64le (ELFv2)

CC: libav-stable@libav.org
Signed-off-by: Martin Storsjö <martin@martin.st>
rtpenc_chain: Don't copy the time base to the source stream by default

Only copy it manually in the muxers where it makes sense (rtspenc,
sapenc). Don't touch the original AVStream in movenchint, where
the original AVStream should be kept untouched.

This fixes the normal tracks in RTP hinted files after
abb810db - the hint tracks were ok while the normal media tracks
were broken, noticed by Michael Niedermayer.

This reverts abb810db but achieves the same effect for the other
muxers.

Signed-off-by: Martin Storsjö <martin@martin.st>