message: Check for KHR_debug when calling glDebugMessageCallback
diff: @@ -759,7 +759,7 @@ WrappedOpenGL::WrappedOpenGL(const char *logfile, const GLHookSet &funcs) : m_Re
  }
  // once GL driver is more tested, this can be disabled
  - if(m_Real.glDebugMessageCallback)
  + if(ExtensionSupported[GLExt_KHR_debug] && m_Real.glDebugMessageCallback)
  {
  m_Real.glDebugMessageCallback(&DebugSnoopStatic, this);
  #if ENABLED(RDOC_DEVEL)
  @@ -1347,7 +1347,8 @@ void WrappedOpenGL::ActivateContext(GLWindowingData winData)
  const GLHookSet &gl = m_Real;
  - if(gl.glDebugMessageCallback && RenderDoc::Inst().GetCaptureOptions().APIValidation)
  + if(ExtensionSupported[GLExt_KHR_debug] && gl.glDebugMessageCallback &&
  + RenderDoc::Inst().GetCaptureOptions().APIValidation)
  {
  gl.glDebugMessageCallback(&DebugSnoopStatic, this);
  gl.glEnable(eGL_DEBUG_OUTPUT_SYNCHRONOUS);
  