Auto merge of #5480 - alexcrichton:fix-regr, r=matklad

Fix optional deps in multiple sections

This commit fixes an issue where an optional dependency was listed multiple
times in a manifest (multiple sections). This regression was introduced by #5415
and happened because in the resolver we didn't record a `Dependency` as it was
accidentally deduplicated too soon.

The fix here was to ensure that all `Dependency` annotations make their way into
`Resolve` now that we rely on the listed `Dependency` values for correctness.

Closes #5475

diff --cc tests/testsuite/build_script.rs
Simple merge