Replace OwningPtr with std::unique_ptr.

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

llvm-svn: 203279
diff --git a/clang/lib/StaticAnalyzer/Checkers/NSAutoreleasePoolChecker.cpp b/clang/lib/StaticAnalyzer/Checkers/NSAutoreleasePoolChecker.cpp
index f857007..b180c03 100644
--- a/clang/lib/StaticAnalyzer/Checkers/NSAutoreleasePoolChecker.cpp
+++ b/clang/lib/StaticAnalyzer/Checkers/NSAutoreleasePoolChecker.cpp
@@ -32,7 +32,7 @@
 namespace {
 class NSAutoreleasePoolChecker
   : public Checker<check::PreObjCMessage> {
-  mutable OwningPtr<BugType> BT;
+  mutable std::unique_ptr<BugType> BT;
   mutable Selector releaseS;
 
 public: