ruby: fixed Set.cc bug to allow zero sized sets This is necessary for example when no dma sequencers are necessary in the simulated system.
ruby: fixed Set.cc bug to allow zero sized sets
This is necessary for example when no dma sequencers are necessary in the
simulated system.

LingxiaoJIA/gem5,haowu4682/gem5,haowu4682/gem5,haowu4682/gem5,haowu4682/gem5,haowu4682/gem5,haowu4682/gem5,LingxiaoJIA/gem5,LingxiaoJIA/gem5,LingxiaoJIA/gem5,haowu4682/gem5,LingxiaoJIA/gem5,LingxiaoJIA/gem5,haowu4682/gem5,LingxiaoJIA/gem5,haowu4682/gem5