Fix tracediff to work with new parameter and output directory structure.
Fix tracediff to work with new parameter and output directory structure.

util/tracediff:
    Fix to work with new parameter and output directory structure.

LingxiaoJIA/gem5,andrewfu0325/gem5-aladdin,haowu4682/gem5,haowu4682/gem5,LingxiaoJIA/gem5,haowu4682/gem5,andrewfu0325/gem5-aladdin,andrewfu0325/gem5-aladdin,LingxiaoJIA/gem5,haowu4682/gem5,haowu4682/gem5,LingxiaoJIA/gem5,andrewfu0325/gem5-aladdin,andrewfu0325/gem5-aladdin,LingxiaoJIA/gem5,LingxiaoJIA/gem5,haowu4682/gem5,haowu4682/gem5,LingxiaoJIA/gem5,andrewfu0325/gem5-aladdin,haowu4682/gem5,haowu4682/gem5,andrewfu0325/gem5-aladdin