Fix need_dev_deps to return false during a default `cargo build` run
Fix need_dev_deps to return false during a default `cargo build` run

- Also add a mode param to need_dev_deps to make clear the intent

vojtechkral/cargo,rust-lang/cargo,nipunn1313/cargo,rustyhorde/cargo,tshepang/cargo,rust-lang/cargo,rustyhorde/cargo,nipunn1313/cargo,tsurai/cargo,eminence/cargo,tsurai/cargo,nipunn1313/cargo,nipunn1313/cargo,tsurai/cargo,tshepang/cargo,tshepang/cargo,eminence/cargo,tsurai/cargo,rustyhorde/cargo,rust-lang/cargo,vojtechkral/cargo,eminence/cargo,vojtechkral/cargo,vojtechkral/cargo,tsurai/cargo,rust-lang/cargo,eminence/cargo,tshepang/cargo,rustyhorde/cargo