7d097a0f had the same purpose as
3700f655 but the former is much simpler, so
let's remove the latter.

Unfortunately both checks were wrong, because in order to make sure DTS > PCR
we have to give us some headroom, so instead of using a dts_difference <
max_delay check let's use a dts_difference < max_delay/2 check.

Fixes DTS < PCR errors with this command line:

./ffmpeg -loglevel verbose -y -f lavfi -i \
  "testsrc=s=64x64:d=20,split=2[out0][tmp1];[tmp1]vflip[out1];sine=d=20,asetnsamples=1000[out2]" \
  -flags +bitexact -fflags +bitexact -sws_flags +accurate_rnd+bitexact  \
  -codec:v libx264 -codec:a mp2 -b:a 32k -pix_fmt yuv420p \
  -map '0:v:0' \
  -map '0:v:1' \
  -map '0:a:0'  \
  -muxrate 800000 \
  -program st=0:st=2 -program st=1:st=2 -program st=2 -program st=0 -f mpegts out1.ts
Signed-off-by: Marton Balint <cus@passwd.hu>