message: Fix fetching glXCreateContextAttribsARB on mesa which was broken
  * The function isn't exported via dlsym, so it needs to be fetched via
  glXGetProcAddress. Calling our own internal wrapper will fetch the
  real pointer and populate it.
diff: @@ -767,7 +767,7 @@ bool OpenGLHook::PopulateHooks()
  {
  SetupHooks();
  - glXGetProcAddress_real((const GLubyte *)"glXCreateContextAttribsARB");
  + glXGetProcAddress((const GLubyte *)"glXCreateContextAttribsARB");
  return SharedPopulateHooks(
  [](const char *funcName) { return (void *)glXGetProcAddress((const GLubyte *)funcName); });
  