Broken link to no-longer-extant `has_any_child_of`

[anp]

CI is failing on an unrelated part of my change, and it looks like the has_any_child_of query linked in https://github.com/rust-lang/rustc-dev-guide/blob/master/src/borrow_check/moves_and_initialization/move_paths.md#cross-references no longer exists. If it had just moved I could add a commit to my PR taking care of that but I'm not sure how to change this text to in order to reflect whatever changed to remove that query.

Halp?

[eddyb]

cc @ecstatic-morse