Use llvm::stable_sort

While touching the code, simplify if feasible.

llvm-svn: 358996
diff --git a/llvm/lib/ProfileData/SampleProfWriter.cpp b/llvm/lib/ProfileData/SampleProfWriter.cpp
index 8135feb..8b876e0 100644
--- a/llvm/lib/ProfileData/SampleProfWriter.cpp
+++ b/llvm/lib/ProfileData/SampleProfWriter.cpp
@@ -50,9 +50,8 @@
   for (const auto &I : ProfileMap)
     V.push_back(std::make_pair(I.getKey(), &I.second));
 
-  std::stable_sort(
-      V.begin(), V.end(),
-      [](const NameFunctionSamples &A, const NameFunctionSamples &B) {
+  llvm::stable_sort(
+      V, [](const NameFunctionSamples &A, const NameFunctionSamples &B) {
         if (A.second->getTotalSamples() == B.second->getTotalSamples())
           return A.first > B.first;
         return A.second->getTotalSamples() > B.second->getTotalSamples();