Make `.rmeta` file in `dep-info` have correct name (`lib` prefix) Since `filename_for_metadata()` and `OutputFilenames::path(OutputType::Metadata)` had different logic for the name of the metadata file, the `.d` file contained a file name different from the actual name used. Share the logic to fix the out-of-sync name. Without this fix, the `.d` file contained dash-separated_something-extra.rmeta: dash-separated.rs instead of libdash_separated_something-extra.rmeta: dash-separated.rs which is the name of the file that is actually written by the compiler. Worth noting: It took me several iterations to get all tests to pass, so I am relatively confident that this PR does not break anything. Closes #68839