message: Add a debug message when KHR_debug is not available for API validation
diff: @@ -2411,6 +2411,20 @@ void WrappedOpenGL::AttemptCapture()
  m_DebugMessages.clear();
  + if(!HasExt[KHR_debug] && RenderDoc::Inst().GetCaptureOptions().apiValidation)
  + {
  + DebugMessage msg = {};
  +
  + msg.category = MessageCategory::Portability;
  + msg.severity = MessageSeverity::High;
  + msg.source = MessageSource::RuntimeWarning;
  + msg.description =
  + "API Validation was enabled, but KHR_debug was not available in this driver so no "
  + "validation messages could be retrieved";
  +
  + m_DebugMessages.push_back(msg);
  + }
  +
  {
  RDCDEBUG("GL Context %llu Attempting capture", m_ContextResourceID);
  