qobject.h has #include <chrono>, which #includes <ctime>, which includes
<time.h>.
datetime.cpp:2621:23: error: 'localtime_r' was not declared in this scope; did you mean 'localtime_s'?
Pick-to: 6.2
Change-Id: I2bbf422288924c198645fffd16a922719c4ce7d4
Reviewed-by: Edward Welbourne <edward.welbourne@qt.io>