Painting: Avoid endless loop for certain bezier curves

If the coordinates were too close (at the limit of the number
accuracy), the splitting algorithm in QBezier::shifted() would never
finish. Ref. testcase in bugreport.

Task-number: QTBUG-44674
Change-Id: I2a575cdc6284504ef5e3eb2b749857576fe433c3
Reviewed-by: Gunnar Sletta <gunnar@sletta.org>

src/gui/painting/qbezier.cpp

@@ -402,8 +402,8 @@ int QBezier::shifted(QBezier *curveSegments, int maxSegments, qreal offset, floa
     Q_ASSERT(curveSegments);
     Q_ASSERT(maxSegments > 0);
 
-    if (x1 == x2 && x1 == x3 && x1 == x4 &&
-        y1 == y2 && y1 == y3 && y1 == y4)
+    if (qFuzzyCompare(x1, x2) && qFuzzyCompare(x1, x3) && qFuzzyCompare(x1, x4) &&
+        qFuzzyCompare(y1, y2) && qFuzzyCompare(y1, y3) && qFuzzyCompare(y1, y4))
         return 0;
 
     --maxSegments;