Add GOP parallelism to the Random Access (RA) CTC.
Add GOP parallelism to the Random Access (RA) CTC.

When running the Random Access (RA) CTC, each input file of 130 frames
 is encoded as two separate GOPs of 65 frames in parallel and the
 resulting OBU files are merged before processing.
This patch forces --limit=130 to prevent users from overriding this
 parameter and producing invalid output.

tdaede/rd_tool,tdaede/rd_tool