Fix GCC 8 warning in qvariantanimation

qtbase/src/corelib/animation/qvariantanimation.cpp:451:13: error: cast between incompatible function types from ‘QVariant (*)(const QRectF&, const QRectF&, qreal)’ {aka ‘QVariant (*)(const QRectF&, const QRectF&, double)’} to ‘QVariantAnimation::Interpolator’ {aka ‘QVariant (*)(const void*, const void*, double)’} [-Werror=cast-function-type]

Change-Id: I5398316adaa0f12fbbdfdb200fd796de284821ef
Reviewed-by: Simon Hausmann <simon.hausmann@qt.io>

src/corelib/animation/qvariantanimation.cpp

@@ -448,7 +448,7 @@ void QVariantAnimation::registerInterpolator(QVariantAnimation::Interpolator fun
 
 template<typename T> static inline QVariantAnimation::Interpolator castToInterpolator(QVariant (*func)(const T &from, const T &to, qreal progress))
 {
-     return reinterpret_cast<QVariantAnimation::Interpolator>(func);
+     return reinterpret_cast<QVariantAnimation::Interpolator>(reinterpret_cast<void *>(func));
 }
 
 QVariantAnimation::Interpolator QVariantAnimationPrivate::getInterpolator(int interpolationType)