rustc: Fix naming output files with --crate-name

The output file was only being renamed based off #[crate_name], not #[crate_id]
or --crate-name. Both of these behaviors have been restored now.
auto merge of #15518 : alexcrichton/rust/fix-some-crate-names, r=sfackler

The output file was only being renamed based off #[crate_name], not #[crate_id]
or --crate-name. Both of these behaviors have been restored now.