Windows: QWindowsOpenGLContextFormat::current() relies on glGetString(GL_VERSION) which returns null in some circumstances

Windows: QWindowsOpenGLContextFormat::current() relies on glGetString(GL_VERSION) which returns null in some circumstances. For example the following:

#include <QApplication>
#include <QByteArray>
#include <QDebug>
#include <QtOpenGL>

int main(int argc, char **argv)
{
QApplication a(argc, argv);
const GLubyte *s = glGetString(GL_VERSION);
qDebug() << QByteArray((const char *)s);
return 0;
}

will return a valid version with 32bit mode but not on 64bit mode on Windows 7. When a valid context exists then it will work fine. Therefore there should be a check in current() to ensure that a temporary context is created if it originally returns null to force it's hand.