Auto merge of #3443 - matklad:path-dep-non-ws, r=alexcrichton

Path deps outside workspace are not members

closes #3192

This implements @Boscop suggestion: path dependencies pointing outside the workspace are never members.

Not sure that it handled #3192 fully: you can't exclude a path dependency within workspace. Not sure this is super useful though...

diff --cc src/doc/manifest.md
Simple merge