change the strange MetadataContext::getMDs function to expose less

irrelevant internal implementation details to clients.

llvm-svn: 92210

llvm/lib/Bitcode/Writer/BitcodeWriter.cpp

@@ -562,7 +562,7 @@ static void WriteMetadataAttachment(const Function &F,
   // Write metadata attachments
   // METADATA_ATTACHMENT - [m x [value, [n x [id, mdnode]]]
   MetadataContext &TheMetadata = F.getContext().getMetadata();
-  typedef SmallVector<std::pair<unsigned, TrackingVH<MDNode> >, 2> MDMapTy;
+  typedef SmallVector<std::pair<unsigned, MDNode*>, 2> MDMapTy;
   MDMapTy MDs;
   for (Function::const_iterator BB = F.begin(), E = F.end(); BB != E; ++BB)
     for (BasicBlock::const_iterator I = BB->begin(), E = BB->end();