CPP1117 — Change struct VariableExt constructor

Instead of `VariableExt(const Variable&, bool);` it should be `VariableExt(Variable, bool);` so that in the implementation we can use std::move, this is as all complex types are passed into the constructor of a struct

In example code, function signature of constructors is non-normative

In section 6.31.3 make it clear that the specific types of the constructor parameters (if they use pass by value or pass by const-reference) is up to the implementation.