Skip baselines earlier in the evaluator

We know that we'll throw them away anyway, so there is no point in even sending them to Sender and comparing them with others once we used them for the best candidate size.

src/evaluate.rs

@@ -24,8 +24,6 @@ use std::thread;
 
 struct Candidate {
     image: PngData,
-    // if false, that's baseline file to throw away
-    is_reduction: bool,
     filter: u8,
     // first wins tie-breaker
     nth: usize,
@@ -62,7 +60,7 @@ impl Comparator {
             true
         };
         if is_best {
-            self.best_result = if new.is_reduction { Some(new) } else { None };
+            self.best_result = Some(new);
         }
     }
 
@@ -162,6 +160,10 @@ impl Evaluator {
                     &deadline,
                 ) {
                     best_candidate_size.set_min(idat_data.len());
+                    // ignore baseline images after this point
+                    if !is_reduction {
+                        return;
+                    }
                     // the rest is shipped to the evavluation/collection thread
                     let new = Candidate {
                         image: PngData {
@@ -169,7 +171,6 @@ impl Evaluator {
                             raw: Arc::clone(&image),
                         },
                         filter,
-                        is_reduction,
                         nth,
                     };