[C++11] Replace llvm::next and llvm::prior with std::next and std::prev.

Remove the old functions.

llvm-svn: 202636
diff --git a/llvm/lib/CodeGen/IfConversion.cpp b/llvm/lib/CodeGen/IfConversion.cpp
index b664b3b..e5b4b23 100644
--- a/llvm/lib/CodeGen/IfConversion.cpp
+++ b/llvm/lib/CodeGen/IfConversion.cpp
@@ -921,7 +921,7 @@
 /// next block).
 static bool canFallThroughTo(MachineBasicBlock *BB, MachineBasicBlock *ToBB) {
   MachineFunction::iterator PI = BB;
-  MachineFunction::iterator I = llvm::next(PI);
+  MachineFunction::iterator I = std::next(PI);
   MachineFunction::iterator TI = ToBB;
   MachineFunction::iterator E = BB->getParent()->end();
   while (I != TI) {