Clippy cleanups

Author: sourcefrog

src/blockdir.rs

@@ -292,7 +292,7 @@ impl BlockDir {
         stats.block_error_count += results.iter().filter(|o| o.is_none()).count();
         let len_map: HashMap<BlockHash, usize> = results
             .into_iter()
-            .filter_map(std::convert::identity) // keep only Some values
+            .flatten() // keep only Some values
             .collect();
         Ok(len_map)
     }

src/gc_lock.rs

@@ -37,11 +37,11 @@ const GC_LOCK: &str = "GC_LOCK";
 
 #[derive(Debug)]
 pub struct GarbageCollectionLock {
+    archive: Archive,
+
     /// Last band id present when the guard was created. May be None if
     /// there are no bands.
     band_id: Option<BandId>,
-
-    archive: Archive,
 }
 
 /// Lock on an archive for gc, that excludes backups and gc by other processes.