Add std:: to sort calls.

llvm-svn: 43652
diff --git a/llvm/lib/Transforms/Utils/LowerSwitch.cpp b/llvm/lib/Transforms/Utils/LowerSwitch.cpp
index faa4e55..3c08edf 100644
--- a/llvm/lib/Transforms/Utils/LowerSwitch.cpp
+++ b/llvm/lib/Transforms/Utils/LowerSwitch.cpp
@@ -244,7 +244,7 @@
     Cases.push_back(CaseRange(SI->getSuccessorValue(i),
                               SI->getSuccessorValue(i),
                               SI->getSuccessor(i)));
-  sort(Cases.begin(), Cases.end(), CaseCmp());
+  std::sort(Cases.begin(), Cases.end(), CaseCmp());
 
   // Merge case into clusters
   if (Cases.size()>=2)