statistics.hh: change VectorDistProxy name to DistProxy - to be more consistent with other proxy namings.
statistics.hh:
change VectorDistProxy name to DistProxy - to be more consistent with other proxy namings.

base/statistics.hh:
    change VectorDistProxy name to DistProxy - to be more consistent with other proxy namings.

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