Use llvm::stable_sort

While touching the code, simplify if feasible.

llvm-svn: 358996
diff --git a/llvm/lib/Transforms/Instrumentation/MaximumSpanningTree.h b/llvm/lib/Transforms/Instrumentation/MaximumSpanningTree.h
index 19035ff..892a6a2 100644
--- a/llvm/lib/Transforms/Instrumentation/MaximumSpanningTree.h
+++ b/llvm/lib/Transforms/Instrumentation/MaximumSpanningTree.h
@@ -67,8 +67,7 @@
     /// MaximumSpanningTree() - Takes a vector of weighted edges and returns a
     /// spanning tree.
     MaximumSpanningTree(EdgeWeights &EdgeVector) {
-
-      std::stable_sort(EdgeVector.begin(), EdgeVector.end(), EdgeWeightCompare());
+      llvm::stable_sort(EdgeVector, EdgeWeightCompare());
 
       // Create spanning tree, Forest contains a special data structure
       // that makes checking if two nodes are already in a common (sub-)tree