From: Yaron Cohen-Tal <yaronct@gmail.com>
Date: Fri, 29 Jul 2016 17:55:49 +0300
Subject: [PATCH] Fox some X server not supporting any OpenGL feature,
 glXQueryExtensionsString will return NULL and causes the function to fail.
 Thanx to Emmanuel Stapf (manus@eiffel.com) for the original patch.

This was verified running an application on macOS while the X server was running
on Windows Xming 7.5.0.10
---
 src/dispatch_common.c | 2 ++
 1 file changed, 2 insertions(+)

--- a/src/dispatch_common.c
+++ b/src/dispatch_common.c
@@ -347,6 +347,8 @@
 bool
 epoxy_extension_in_string(const char *extension_list, const char *ext)
 {
+    if (!extension_list)
+        return false;
     const char *ptr = extension_list;
     int len = strlen(ext);