[llvm-pdbdump] Dump stream summary list.

Try to figure out what each stream is, and dump its name.

This gives us a better picture of what streams we still don't
understand.

llvm-svn: 270653
diff --git a/llvm/lib/DebugInfo/PDB/Raw/NameMap.cpp b/llvm/lib/DebugInfo/PDB/Raw/NameMap.cpp
index b3bd94c..202e717 100644
--- a/llvm/lib/DebugInfo/PDB/Raw/NameMap.cpp
+++ b/llvm/lib/DebugInfo/PDB/Raw/NameMap.cpp
@@ -127,6 +127,11 @@
   return Error::success();
 }
 
+iterator_range<StringMapConstIterator<uint32_t>> NameMap::entries() const {
+  return llvm::make_range<StringMapConstIterator<uint32_t>>(Mapping.begin(),
+                                                            Mapping.end());
+}
+
 bool NameMap::tryGetValue(StringRef Name, uint32_t &Value) const {
   auto Iter = Mapping.find(Name);
   if (Iter == Mapping.end())