Reported path for unresolved named imports is wrong

[brson]

// error-pattern:unresolved import: m::f
import x = m::f;

mod m {
}

fn main() {
}

../src/test/compile-fail/unresolved-named-import.rs:2:7: 2:16 error: unresolved import: m::x
../src/test/compile-fail/unresolved-named-import.rs:2 import x = m::f;

The error says we failed to resolve m::x but that is incorrect. We failed to resolve x, we failed to find m::f, and m::x doesn't identify a real thing.

[catamorphism]

Test after #1935 is done.

[bstrie]

The example file no longer fails to compile, although shouldn't it? After all, there's still nothing named m::f for it to import.

[catamorphism]

Yes, it should fail to compile, so there's a different bug now.

[catamorphism]

This test passes now.