If this ever happens, we clearly have a bug, so print out proper warning,
instead of silently crashing the Xserver.
| ../glx/glxcmds.c: In function ‘validGlxFBConfigForWindow’:
| ../glx/glxcmds.c:127:16: warning: dereference of NULL ‘pVisual’ [CWE-476] [-Wanalyzer-null-dereference]
| 127 | if (pVisual->class != glxConvertToXVisualType(config->visualType) ||
| | ~~~~~~~^~~~~~~
Signed-off-by: Enrico Weigelt, metux IT consult <info@metux.net>