X11DRV: don't read NULL struct

[Saulius Krasuckas]

This occures in 8 bit mode with binary (native) NVIDIA driver.


Log message:
	Saulius Krasuckas <saulius.krasuckas at ieee.org>
	Don't read non-existing struct.


Index: dlls/x11drv/opengl.c
===================================================================
RCS file: /home/wine/wine/dlls/x11drv/opengl.c,v
retrieving revision 1.12
diff -p -u -4 -r1.12 opengl.c
--- dlls/x11drv/opengl.c        16 Aug 2005 16:02:45 -0000      1.12
+++ dlls/x11drv/opengl.c        21 Aug 2005 16:44:16 -0000
@@ -491,8 +491,9 @@ XVisualInfo *X11DRV_setup_opengl_visual(
         wine_tsx11_unlock();
         if (visual == NULL) {
             /* This should only happen if we cannot find a match with a depth size 16 */
             FIXME("Failed to find a suitable visual\n");
+            return visual;
         }
     }
     TRACE("Visual ID %lx Chosen\n",visual->visualid);
     return visual;