Build, but do not link dynamic libraries

[idubrov]

Describe the problem you are trying to solve

I have a main binary and set of cdylib plugins. I want cdylib plugins to be built every time (as necessary, after doing all up-to-date checks) I run main binary, but without doing any linking.

Describe the solution you'd like

Basically, I want to have a dependency like:

[???-dependencies]
my-nice-plugin = { path = "../plugin" }

So every time I do cargo run --package main, cargo will also implicitly do cargo build --package my-nice-plugin to produce a loadable library.

[epage]

I believe #9096 covers this. Closing in favor of that. If there is a reason for us to reconsider, let us know!