Now the same pipeline for handling the audio/videos streams will handle
the segmented text streams too. This doesn't apply to the text output,
only to the MP4 variants. This also fixes a bug where we added the
X-TIMESTAMP-MAP tag even when there wasn't TS streams; this doesn't
otherwise change the behavior around that tag.
Change-Id: I03f7cea56efa42e96311c00841330629a14aa053
Jacob Trimble