message: Add explicit lifetimes to Executor::init.
diff: @@ -60,7 +60,7 @@ pub trait Executor: Send + Sync + 'static {
  /// Called after a rustc process invocation is prepared up-front for a given
  /// unit of work (may still be modified for runtime-known dependencies, when
  /// the work is actually executed).
  - fn init(&self, _cx: &Context<'_, '_>, _unit: &Unit<'_>) {}
  + fn init<'a, 'cfg>(&self, _cx: &Context<'a, 'cfg>, _unit: &Unit<'a>) {}
  /// In case of an `Err`, Cargo will not continue with the build process for
  /// this package.
  