fix the failing regression.  the sconscript ("makefile") was missing the etherbus.cc src file.
fix the failing regression.  the sconscript ("makefile") was missing the etherbus.cc src file.

SConscript:
    THIS is why the regression keeps failing.  it's missing the the etherbus file in the sconscript.

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