Use qFuzzyCompare instead of qFuzzyIsNull in QPointF ==

qFuzzyIsNull has a fixed range, where qFuzzyCompare can tell if numbers
are different in a more relative range. Without it QPointFs that are
heavily scaled will be interpreted as identical, when they are quite
different at their own scale.

Task-number: QTBUG-60359
Task-number: QTBUG-62161
Change-Id: Ic4ba90e9e994aedff5548d690f053eb309b0a60b
Reviewed-by: Edward Welbourne <edward.welbourne@qt.io>
Reviewed-by: Thiago Macieira <thiago.macieira@intel.com>