update machinery: complete transition

update machinery: complete transition

* Drop all need_mask alterations (no idea why there were here at all,
  but surely not sane since they are missing in the non-linux
  functions).
* Drop the update delay for update_meminfo(), as parsing /proc should
  not lead to abnormal overhead.
* Check for x_initialised from inside update_x11info(), so we can call
  it unconditionally.