QNonContiguousByteDevice: roll back complete internal state in reset()

... otherwise we would not start reading from the beginning when the
device was reset.

Change-Id: Ida196eb40790fba56ff2eed782fd93a3015222f9
Reviewed-by: Shane Kearns <shane.kearns@accenture.com>

src/corelib/io/qnoncontiguousbytedevice.cpp

@@ -391,6 +391,13 @@ bool QNonContiguousByteDeviceIoDeviceImpl::reset()
     bool reset = (initialPosition == 0) ? device->reset() : device->seek(initialPosition);
     if (reset) {
         eof = false; // assume eof is false, it will be true after a read has been attempted
+        totalAdvancements = 0; //reset the progress counter
+        if (currentReadBuffer) {
+            delete currentReadBuffer;
+            currentReadBuffer = 0;
+        }
+        currentReadBufferAmount = 0;
+        currentReadBufferPosition = 0;
         return true;
     }