Patch - Change order of declaration of QScopedPointer's in q_supportsElementIndexUint

I've been having a crash (segfault) in a project using QML. The crash happens in an embedded machine running a yocto generated image, using eglfs. The embedded machine is a regular PC based on an Intel processor, running QT 5.12.2 and Linux 4.19.13. I was able to determine that using the QML type ShapePath with a non-transparent fillColor property triggered the segfault, but unfortunately I couln't reproduce it outside the target machine, not even in a fedora machine running the same library version and under eglfs.

Anyway, by debugging the application directly in the target machine, I could pinpoint the source of the problem:

        if (!elementIndexUintChecked) {
            elementIndexUintChecked = true;
            QOpenGLContext *context = QOpenGLContext::currentContext();
            QScopedPointer<QOpenGLContext> dummyContext;
            QScopedPointer<QOffscreenSurface> dummySurface;
            bool ok = true;
            if (!context) {
                dummyContext.reset(new QOpenGLContext);
                dummyContext->create();
                context = dummyContext.data();
                dummySurface.reset(new QOffscreenSurface);
                dummySurface->setFormat(context->format());
                dummySurface->create();
                ok = context->makeCurrent(dummySurface.data());
            }
            if (ok) {
                elementIndexUint = static_cast<QOpenGLExtensions *>(context->functions())->hasOpenGLExtension(
                            QOpenGLExtensions::ElementIndexUint);
            }
        }

This code snippet is from the file src/quickshapes/qquickshapegenericrenderer.cpp in qtdeclarative. The problem, I think, is that the smart pointers dummyContext and dummySurface are declared in the incorrect order. If QOpenGLContext::currentContext() returns nullptr, then dummyContext is destroyed after dummySurface is destroyed, so during the destruction it is holding a pointer to an invalid object. I'm not sure if this is safe or not, since I don't fully understand what happens during the destruction of a QOpenGLContext, but what I know is that changing the order of declaration fixes the crash. Perhaps someone with better understanding can validate this. In any case, I'm submitting a patch that does just that.

If anything else is needed (backtraces, core dumps, versions) please ask.