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
Andrzej Kotulski