[C++ models] Fix compilation errors with make_shared/unique

Summary:
Some classes may have deleted new operator for them. To fix it, run global `new` operator instead
```
struct X {
  void* operator new(size_t) = delete;
};

X *p = new X; // compilation error
X *p = ::new X; // no compilation error
```

This change is following same strategy standard headers follow.

Reviewed By: jvillard

Differential Revision: D4500977

fbshipit-source-id: 20babfa

infer/models/cpp/include/infer_model/shared_ptr.h

@@ -405,7 +405,7 @@ class enable_shared_from_this : public std__enable_shared_from_this<T> {
 
 template <class T, class... Args>
 shared_ptr<T> make_shared(Args&&... args) {
-  return shared_ptr<T>(new T(std::forward<Args>(args)...));
+  return shared_ptr<T>(::new T(std::forward<Args>(args)...));
 }
 
 #undef __cast_to_infer_ptr

infer/models/cpp/include/infer_model/unique_ptr.h

@@ -446,13 +446,13 @@ struct _MakeUniq2<_Tp[_Bound]> {
 template <typename _Tp, typename... _Args>
 inline typename _MakeUniq2<_Tp>::__single_object make_unique(
     _Args&&... __args) {
-  return unique_ptr<_Tp>(new _Tp(std::forward<_Args>(__args)...));
+  return unique_ptr<_Tp>(::new _Tp(std::forward<_Args>(__args)...));
 }
 
 /// std::make_unique for arrays of unknown bound
 template <typename _Tp>
 inline typename _MakeUniq2<_Tp>::__array make_unique(size_t __num) {
-  return unique_ptr<_Tp>(new typename remove_extent<_Tp>::type[__num]());
+  return unique_ptr<_Tp>(::new typename remove_extent<_Tp>::type[__num]());
 }
 
 /// Disable std::make_unique for arrays of known bound