Replace OwningPtr with std::unique_ptr.

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

llvm-svn: 203279
diff --git a/clang/lib/Frontend/MultiplexConsumer.cpp b/clang/lib/Frontend/MultiplexConsumer.cpp
index 89aeeb4..ca7e6d3 100644
--- a/clang/lib/Frontend/MultiplexConsumer.cpp
+++ b/clang/lib/Frontend/MultiplexConsumer.cpp
@@ -184,10 +184,9 @@
 
 }  // end namespace clang
 
-
-MultiplexConsumer::MultiplexConsumer(ArrayRef<ASTConsumer*> C)
-    : Consumers(C.begin(), C.end()),
-      MutationListener(0), DeserializationListener(0) {
+MultiplexConsumer::MultiplexConsumer(ArrayRef<ASTConsumer *> C)
+    : Consumers(C.begin(), C.end()), MutationListener(),
+      DeserializationListener() {
   // Collect the mutation listeners and deserialization listeners of all
   // children, and create a multiplex listener each if so.
   std::vector<ASTMutationListener*> mutationListeners;