tests: Test that `extern "C" fn` ptrs lint on slices This seems to have slipped past the `improper_ctypes_definitions` lint at some point. I found similar tests but not one with this exact combination, so test the semi-unique combination.
clippy::needless_lifetimes
non_snake_case
Stmt
extern "C" fn
missing_docs
--test
doc(hidden)
allow(missing_docs)