Remove a now-unneeded QT_NO_OPENGL ifdef

This is from a fix unrelated to the recent rhi-based composition
work, which means it still had to enclose the block in an ifdef
due to the variables being only present in OpenGL-enabled builds.
Now with the other patches in place, the variables are no longer
conditional, and the similar ifndef QT_NO_OPENGL checks are already
gone pretty much everywhere so the ifdef is not needed here either.

Change-Id: I497c7a4fad7cd7d8fc1a479e7032de3e2cbb3b32
Reviewed-by: Andy Nichols <andy.nichols@qt.io>

src/widgets/kernel/qwidget.cpp

@@ -11051,12 +11051,10 @@ void QWidgetPrivate::update(T r)
 {
     Q_Q(QWidget);
 
-#ifndef QT_NO_OPENGL
     if (renderToTexture && !q->isVisible()) {
         renderToTextureReallyDirty = 1;
         return;
     }
-#endif
 
     if (!q->isVisible() || !q->updatesEnabled())
         return;