Issue 4391: rustc should not silently skip tests with erroneous signature.
mod items need to be marked with `cfg(test)` not `test`.
mod items need to be marked with `cfg(test)` not `test`.
auto merge of #6111 : pnkfelix/rust/issue4391-rustc-should-not-silently-skip-erroneous-tests, r=pnkfelix

...e.

Fixes #4391.