Mesa Intel decode tool updates for debug purpose.

• sometime we want to show unknown instructions for debug purpose, e.g. buffer overlap/occupation, so we enable decode tool to show all unknown contents in this MR.
• sometime there has no original second BB entry due to decode tool don't show ring from the begining, we show full ring buffer now.

@jljusten @llandwerlin could you help on review and provide your comments here, thank you very much！