message: Fix wrong FBO attachment being specified for readback
diff: @@ -326,7 +326,7 @@ void GLReplay::GetOutputWindowData(uint64_t id, bytebuf &retData)
  MakeCurrentReplayContext(m_DebugCtx);
  m_pDriver->glBindFramebuffer(eGL_READ_FRAMEBUFFER, outw.BlitData.windowFBO);
  - m_pDriver->glReadBuffer(eGL_BACK);
  + m_pDriver->glReadBuffer(eGL_COLOR_ATTACHMENT0);
  m_pDriver->glBindBuffer(eGL_PIXEL_PACK_BUFFER, 0);
  m_pDriver->glPixelStorei(eGL_PACK_ROW_LENGTH, 0);
  m_pDriver->glPixelStorei(eGL_PACK_SKIP_ROWS, 0);
  