Merge #2466

2466: Handle partial resolve cases r=matklad a=edwin0cheng

Another try to fix #2443 :

We resolve all imports every time in `DefCollector::collect` loop even it is resolved previously.
This is because other unresolved imports and macros will bring in another `PerNs`, so we can only assume that it has been partially resolved.

Co-authored-by: Edwin Cheng <edwin0cheng@gmail.com>

diff --cc crates/ra_hir_def/src/nameres/collector.rs
Simple merge