Replace OwningPtr with std::unique_ptr.

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

llvm-svn: 203279
diff --git a/clang/unittests/AST/DeclPrinterTest.cpp b/clang/unittests/AST/DeclPrinterTest.cpp
index 5420d96..5340756 100644
--- a/clang/unittests/AST/DeclPrinterTest.cpp
+++ b/clang/unittests/AST/DeclPrinterTest.cpp
@@ -74,7 +74,8 @@
   PrintMatch Printer;
   MatchFinder Finder;
   Finder.addMatcher(NodeMatch, &Printer);
-  OwningPtr<FrontendActionFactory> Factory(newFrontendActionFactory(&Finder));
+  std::unique_ptr<FrontendActionFactory> Factory(
+      newFrontendActionFactory(&Finder));
 
   if (!runToolOnCodeWithArgs(Factory->create(), Code, Args, FileName))
     return testing::AssertionFailure()