[clang] [Clang] Fix a regression introduced by #161163. (PR #162612)

[Andrey Ali Khan Bolshakov via cfe-commits]

bolshakov-a wrote:

What about implicit default constructors, like in this case?
```cpp
struct NonCopyable{
    NonCopyable() = default;
    NonCopyable(const NonCopyable&) = delete;
};

class C {
    NonCopyable nc;
};

//C c;

static_assert(__builtin_is_implicit_lifetime(C));
```

https://github.com/llvm/llvm-project/pull/162612