Auto merge of #3752 - matklad:always-artifacts, r=alexcrichton

Always produce artifact messages

This changes `artifact` messages in several ways:

* They are produced even for fresh builds

* They used the path after hard linking (@jsgf talked about it in the end of https://github.com/rust-lang/cargo/pull/3319#issuecomment-263975431)

* Don't produce filenames if the compiler has not actually produced the binaries (`-Z-no-trans`).