[clang] [Coverage] Handle array decomposition correctly (PR #88881)

[Eli Friedman via cfe-commits]

efriedma-quic wrote:

Say you have:

```
int foo();
struct A { A(); A(const A&, int = foo()); };
struct B { A a[10]; };
void f(const B& b) { B bb = b; }
```

We want to visit the call to foo(), I think?

https://github.com/llvm/llvm-project/pull/88881