Eliminate the SetCCSDNode in favor of a CondCodeSDNode class. This pulls the

Eliminate the SetCCSDNode in favor of a CondCodeSDNode class.  This pulls the
CC out of the SetCC operation, making SETCC a standard ternary operation and
CC's a standard DAG leaf.  This will make it possible for other node to use
CC's as operands in the future...

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@22728 91177308-0d34-0410-b5e6-96231b3b80d8