[Utils] Simplify combineMetadata

Use a range-based for loop, no functional change is intended.

llvm-svn: 276600
diff --git a/llvm/lib/Transforms/Utils/Local.cpp b/llvm/lib/Transforms/Utils/Local.cpp
index f1838d8..4043268 100644
--- a/llvm/lib/Transforms/Utils/Local.cpp
+++ b/llvm/lib/Transforms/Utils/Local.cpp
@@ -1586,10 +1586,10 @@
   SmallVector<std::pair<unsigned, MDNode *>, 4> Metadata;
   K->dropUnknownNonDebugMetadata(KnownIDs);
   K->getAllMetadataOtherThanDebugLoc(Metadata);
-  for (unsigned i = 0, n = Metadata.size(); i < n; ++i) {
-    unsigned Kind = Metadata[i].first;
+  for (const auto &MD : Metadata) {
+    unsigned Kind = MD.first;
     MDNode *JMD = J->getMetadata(Kind);
-    MDNode *KMD = Metadata[i].second;
+    MDNode *KMD = MD.second;
 
     switch (Kind) {
       default: