Fixed a bug that caused check -chunks -persist to succeed with broken chunks

The bug was not setting the `isBroken` flag in WaitForChunk()

src/duplicacy_chunkdownloader.go

@@ -254,6 +254,9 @@ func (downloader *ChunkDownloader) WaitForChunk(chunkIndex int) (chunk *Chunk) {
 		downloader.taskList[completion.chunkIndex].chunk = completion.chunk
 		downloader.numberOfDownloadedChunks++
 		downloader.numberOfDownloadingChunks--
+		if completion.chunk.isBroken {
+			downloader.NumberOfFailedChunks++
+		}
 	}
 	return downloader.taskList[chunkIndex].chunk
 }

src/duplicacy_snapshotmanager.go

@@ -1041,6 +1041,9 @@ func (manager *SnapshotManager) CheckSnapshots(snapshotID string, revisionsToChe
 		totalChunks := len(*allChunkHashes)
 		for i := 0; i < totalChunks; i++ {
 			chunk := manager.chunkDownloader.WaitForChunk(i + chunkIndex)
+			if chunk.isBroken {
+				continue
+			}
 			downloadedChunkSize += int64(chunk.GetLength())
 
 			elapsedTime := time.Now().Sub(startTime).Seconds()