The default scheduling on windows seems fairly erratic or is at least in the
VM that I'm running these tests on, so increase the timing slack a bit so the
test has a better chance of passing. It is still quite easy for it to fail
though, especially if you for instance manipulate the terminal window somehow
while running the tests but it does not really matter in any case as this test
serves its purpose in testing the PBD::MMTimers API.
It looks as if the default timer resolution for applications running under wine
is different than Windows so just test that the minimum timer resolution is
below a certain amount rather than checking before and after calling
timeBeginPeriod
I'm not sure if this test is going to be effective as I don't have hardware to
test on at the moment. As noted in the documentation, Windows XP should be the
only OS where QPC uses a timer source that is non-monotonic(multi-core with
non-syncronized TSC).
