Fix a bug in RegsForValue::getCopyToRegs() that causes cyclical scheduling...

Fix a bug in RegsForValue::getCopyToRegs() that causes cyclical scheduling units. If it's creating multiple CopyToReg nodes that are "flagged" together, it should not create a TokenFactor for it's chain outputs:

c1, f1 = CopyToReg                                                                                                                                                                                             
c2, f2 = CopyToReg                                                                                                                                                                                             
c3     = TokenFactor c1, c2                                                                                                                                                                                    
 ...                                                                                                                                                                                                                      
       = user c3, ..., f2

Now that the two CopyToReg's and the user are "flagged" together. They effectively forms a single scheduling unit. The TokenFactor is now both an operand and a successor of the Flagged nodes.

llvm-svn: 50376