Fix build with MinGW due to -Werror

On Windows the correct format is %I64d and %I64u:
https://stackoverflow.com/questions/2844/how-do-you-printf-an-unsigned-long-long-int

Similar ifdefs are found in testlib/qtestcase.cpp

Change-Id: Ic65e60f7d391285e292ac8c65944d8af3be205f4
Reviewed-by: Friedemann Kleint <Friedemann.Kleint@theqtcompany.com>
Reviewed-by: Simon Hausmann <simon.hausmann@digia.com>