The definition of "deleted definition" in [dcl.fct.def.delete] is not
written in the form of a definition and neither is the definition of
"deleted function". Most problematically, these definitions encompass
only the syntactic case of explicitly deleting a function but the terms
are used where semantic deletedness is meant.

Applying the syntactic interpretation of the definition could lead to
the conclusion that the following is ill-formed:
```cpp
struct A { ~A() = delete; };
struct B {
  A a;
  virtual ~B() = default;
};
struct C : B { virtual ~C() = delete; };
```

This patch changes the definitions to cover semantic deletion.

**Drafting notes:**

- It appears that uses of "deleted definition" in the text is usually
  refer to physical definitions (but not necessarily to explicit
  deletions).
- The increased verbosity is somewhat necessary to meet the ideal that
  uses of a term may be replaced with the definition of the term with
  minimal adjustments.