deccc608sub: fix roll-up subtitles

Roll-up CC timestamps need similar treatment as the popup CC timestamps.
Also, the simulated carriage return command that was added during
a rollup command was inserting blank lines in the CC, so fix that.

git-svn-id: svn://svn.handbrake.fr/HandBrake/trunk@6144 b64f7644-9d1e-0410-96f1-a4d463321fa5