ScheduleDAG: colorize the DOT graph and improve formatting.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@173431 91177308-0d34-0410-b5e6-96231b3b80d8
MachineScheduler support for viewGraph.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@173432 91177308-0d34-0410-b5e6-96231b3b80d8
MIsched: Print block name. No functionality.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@173433 91177308-0d34-0410-b5e6-96231b3b80d8