The threadCount() test function is unstable and had been disabled by
making it not be a slot. It is better to disable it with QSKIP so that
the test output shows that the test function exists and is in need of
repair.
Change-Id: Iccdc8da31e0d15d922f7e9606835d1ff1a3a4966
Reviewed-by: Rohan McGovern <rohan.mcgovern@nokia.com>