segfault after commit GLX: Enable GLX 1.4 on DRI2

[Markus Amsler]

After

commit ad5c0d9efa47476ed5cf75c82265c73919e468b4
Author: Ian Romanick <ian.d.romanick at intel.com>
Date:   Tue Sep 29 16:43:43 2009 -0700
    GLX: Enable GLX 1.4 on DRI2

I'm getting segfaults at server startup in glx/glxext.c:373:

        for (p = __glXProviderStack; p != NULL; p = p->next) {
            __GLXscreen *glxScreen;

            glxScreen = p->screenProbe(pScreen);
            if (glxScreen != NULL) {
                LogMessage(X_INFO,
                           "GLX: Initialized %s GL provider for screen 
%d\n",
                           p->name, i);
                break;
            }

            if (glxScreen->GLXminor < glxMinorVersion)
                glxMinorVersion = glxScreen->GLXminor;
        }


This code doesn't make sense because if glxScreen is NULL it runs 
straight into an segfault with glxScreen->GLXminor

Markus