QQuaternion: fix remaining qFuzzyCompare() precondition violations

qFuzzyCompare() requires that neither argument is numerically
zero. This cannot be guaranteed for the quaternion elements.

Fix by using the new QtPrivate::fuzzyCompare() function, which does
things in the correct way.

As a drive-by, put the operators at the beginning of continued lines,
as requested by https://wiki.qt.io/Qt_Coding_Style#Line_breaks Item 2.

Amends the start of the public history.

Pick-to: 6.10 6.8 6.5
Change-Id: Ia317aa260ffc9fb04c10c24517a1ca3be58a1b05
Reviewed-by: Ivan Solovev <[email protected]>

Author: marcmutz

src/gui/math3d/qquaternion.h

@@ -305,10 +305,10 @@ constexpr QQuaternion operator/(const QQuaternion &quaternion, float divisor)
 
 constexpr bool qFuzzyCompare(const QQuaternion &q1, const QQuaternion &q2) noexcept
 {
-    return qFuzzyCompare(q1.wp, q2.wp) &&
-           qFuzzyCompare(q1.xp, q2.xp) &&
-           qFuzzyCompare(q1.yp, q2.yp) &&
-           qFuzzyCompare(q1.zp, q2.zp);
+    return QtPrivate::fuzzyCompare(q1.wp, q2.wp)
+        && QtPrivate::fuzzyCompare(q1.xp, q2.xp)
+        && QtPrivate::fuzzyCompare(q1.yp, q2.yp)
+        && QtPrivate::fuzzyCompare(q1.zp, q2.zp);
 }
 
 #if QT_GUI_INLINE_IMPL_SINCE(6, 11)