use enumerate when iterating to track index and item

Author: philippem

src/new_index/fetch.rs

@@ -186,10 +186,8 @@ fn blkfiles_reader(blk_files: Vec<PathBuf>, xor_key: Option<[u8; 8]>) -> Fetcher
     Fetcher::from(
         chan.into_receiver(),
         spawn_thread("blkfiles_reader", move || {
-            let mut count = 0;
             let blk_files_len = blk_files.len();
-            for path in blk_files {
-                count += 1;
+            for (count, path) in blk_files.iter().enumerate() {
                 info!("block file reading {:}/{:} {:.2}%",
                     count,
                     blk_files_len,