- Fix a subtle bug in RemoveCopyByCommutingDef. ALR is the live range where...

- Fix a subtle bug in RemoveCopyByCommutingDef. ALR is the live range where the source is defined; BLR is the live range which is defined by the copy.
If ALR and BLR overlaps and end of BLR extends beyond end of ALR, e.g.                                                                                                 
 A = or A, B                                                                                                                                                            
 ...                                                                                                                                                                    
 B = A                                                                                                                                                                  
 ...                                                                                                                                                                    
 C = A<kill>                                                                                                                                                            
 ...                                                                                                                                                                    
   = B                                                                                                                                                                  
                                                                                                                                                                        
then do not add kills of A to the newly created B interval.
- Also fix some kill info update bug.

llvm-svn: 48141