[C++11] Replace llvm::tie with std::tie.

The old implementation is no longer needed in C++11.

llvm-svn: 202644
diff --git a/llvm/lib/CodeGen/LiveIntervalAnalysis.cpp b/llvm/lib/CodeGen/LiveIntervalAnalysis.cpp
index 83d6207..a5cadf4 100644
--- a/llvm/lib/CodeGen/LiveIntervalAnalysis.cpp
+++ b/llvm/lib/CodeGen/LiveIntervalAnalysis.cpp
@@ -459,7 +459,7 @@
 
   MachineBasicBlock *KillMBB = Indexes->getMBBFromIndex(Kill);
   SlotIndex MBBStart, MBBEnd;
-  tie(MBBStart, MBBEnd) = Indexes->getMBBRange(KillMBB);
+  std::tie(MBBStart, MBBEnd) = Indexes->getMBBRange(KillMBB);
 
   // If VNI isn't live out from KillMBB, the value is trivially pruned.
   if (LRQ.endPoint() < MBBEnd) {
@@ -486,7 +486,7 @@
       MachineBasicBlock *MBB = *I;
 
       // Check if VNI is live in to MBB.
-      tie(MBBStart, MBBEnd) = Indexes->getMBBRange(MBB);
+      std::tie(MBBStart, MBBEnd) = Indexes->getMBBRange(MBB);
       LiveQueryResult LRQ = LI->Query(MBBStart);
       if (LRQ.valueIn() != VNI) {
         // This block isn't part of the VNI segment. Prune the search.