RC5: zxing not respecting `-t`

[Zixian Cai]

zxing internally does this

    int numThreads = Math.min(numInputs, Runtime.getRuntime().availableProcessors());
    int successful = 0;    
    if (numThreads > 1) {
      ExecutorService executor = Executors.newFixedThreadPool(numThreads);

and DaCapo's -t has no effect.

[Steve Blackburn]

Fixed in e183405