fix ctts index computation when seeking, check must be done against next ctts sample, thanks to Uoti
fix ctts index computation when seeking, check must be done against next ctts sample, thanks to Uoti

git-svn-id: a4d7c1866f8397a4106e0b57fc4fbf792bbdaaaf@9007 9553f0bf-9b14-0410-a0b8-cfaf0461ba5b

prajnashi/ffmpeg,prajnashi/ffmpeg,prajnashi/ffmpeg,prajnashi/ffmpeg