[macOS] timing is not reliable

[Raffaello]

timing on macOS seems not precise and test are failing on the CI due on late calls to the timer cursor callback.

for macOS skip that check introducing a compiler definition DONT_TEST_PRECISE_TIMING

or HAVE_PRECISE_TIMER

or HAVE_NOT_PRECISE_TIMER

can be used a cmake test functionality during compilation to make it automatic without requiring anothe compiler switch.