cargo-fmt: Fix splitting of targets across editions
cargo-fmt: Fix splitting of targets across editions

When I reworked the code, it ended not generating the complete list of
need targets. Fix it.

Fixes: #3143.

Signed-off-by: Otavio Salvador <1d31b11c1b92bf5d043d36edfe7174db39a6b891@ossystems.com.br>

aidancully/rust,graydon/rust,aidancully/rust,aidancully/rust,aidancully/rust,rust-lang/rustfmt,graydon/rust,graydon/rust,aidancully/rust,graydon/rust,SingingTree/rustfmt,aidancully/rust,graydon/rust,rust-lang/rustfmt,graydon/rust,SingingTree/rustfmt