Yet another attempt to fix DoAtsuiLayout

Still not quite working yet but better and should not trigger crash on
story-zapfino.tex.

- Better handling when justify == 1 and Core Text failed to provide a
  justified line (returns == NULL).
- Include fontletterspace[f] in node_width calculation.
- node_width(node) should be the x position of second to last glyph
  instead of last glyph + lsDelta. (I wonder how do we take the width
  of last glyph into account.)
Fixup to previous patch
Add the last glyphs advance seems to fix the layout problem