Auto merge of #5556 - alexcrichton:fix, r=matklad

Copy `--all-features` request to all workspace members

This fixes an accidental regression introduced in #5012 where the
`--all-features` CLI flag was only propagated to the "main crate" as opposed to
all workspace packages. This behavior has [already been deemed][pr] as
"basically not what you want", but for now it's best to avoid the regression.

Closes #5518

[pr]: https://github.com/rust-lang/cargo/pull/5353