Fix the build after r185363. Use llvm::next instead of raw next.

llvm-svn: 185367
diff --git a/llvm/lib/CodeGen/PHIElimination.cpp b/llvm/lib/CodeGen/PHIElimination.cpp
index 985967e..bf23eca 100644
--- a/llvm/lib/CodeGen/PHIElimination.cpp
+++ b/llvm/lib/CodeGen/PHIElimination.cpp
@@ -222,7 +222,7 @@
                                   MachineBasicBlock::iterator LastPHIIt) {
   ++NumLowered;
 
-  MachineBasicBlock::iterator AfterPHIsIt = next(LastPHIIt);
+  MachineBasicBlock::iterator AfterPHIsIt = llvm::next(LastPHIIt);
 
   // Unlink the PHI node from the basic block, but don't delete the PHI yet.
   MachineInstr *MPhi = MBB.remove(MBB.begin());