QAudioInput elapsedUSecs return value is not qint64

The elapsedUSecs() method from QAudioInput has problems when the number of microseconds exceeds the bounds of an 32bit integer. Then the amount becomes negative. From then on the amount changes from negative to positive at some point, then it again raises up to the 32bit and gets negative again.

I made a simple test application opening an input stream with an notifyInterval of 10,000 microseconds. The interval dumps a timestamp, bytesReady, elapsedUSecs and processedUSecs into a file.

The test was done on a Samsung S4Mini running Android 4.4.2. The dump file is attached.