Function build_work

fn build_work(
    build_runner: &mut BuildRunner<'_, '_>,
    unit: &Unit,
) -> CargoResult<Job>

Constructs the unit of work of running a build script.

The construction includes:

• Set environment variables for the build script run.
• Create the output dir (OUT_DIR) for the build script output.
• Determine if the build script needs a re-run.
• Run the build script and store its output.