Add explicit lifetimes to Executor::init.

src/cargo/core/compiler/mod.rs

@@ -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.