Replace OwningPtr with std::unique_ptr.

This compiles cleanly with lldb/lld/clang-tools-extra/llvm.

llvm-svn: 203279
diff --git a/clang/lib/CodeGen/CGVTables.cpp b/clang/lib/CodeGen/CGVTables.cpp
index 4a381a8..0ad765c 100644
--- a/clang/lib/CodeGen/CGVTables.cpp
+++ b/clang/lib/CodeGen/CGVTables.cpp
@@ -554,7 +554,7 @@
   if (CGDebugInfo *DI = CGM.getModuleDebugInfo())
     DI->completeClassData(Base.getBase());
 
-  OwningPtr<VTableLayout> VTLayout(
+  std::unique_ptr<VTableLayout> VTLayout(
       getItaniumVTableContext().createConstructionVTableLayout(
           Base.getBase(), Base.getBaseOffset(), BaseIsVirtual, RD));