Revert "[codeview] Make obj2yaml/yaml2obj support .debug$S..."

This is causing failures on linux bots with an invalid stream
read.  It doesn't repro in any configuration on Windows, so
reverting until I have a chance to investigate on Linux.

llvm-svn: 305371
diff --git a/llvm/lib/DebugInfo/PDB/Native/DbiModuleDescriptorBuilder.cpp b/llvm/lib/DebugInfo/PDB/Native/DbiModuleDescriptorBuilder.cpp
index 81a9d3e..396dffa 100644
--- a/llvm/lib/DebugInfo/PDB/Native/DbiModuleDescriptorBuilder.cpp
+++ b/llvm/lib/DebugInfo/PDB/Native/DbiModuleDescriptorBuilder.cpp
@@ -177,7 +177,7 @@
 }
 
 void DbiModuleDescriptorBuilder::addDebugSubsection(
-    std::shared_ptr<DebugSubsection> Subsection) {
+    std::unique_ptr<DebugSubsection> Subsection) {
   assert(Subsection);
   C13Builders.push_back(llvm::make_unique<DebugSubsectionRecordBuilder>(
       std::move(Subsection), CodeViewContainer::Pdb));