Log Message:
Updated harfbuzz to 1.4.3.

Overview of changes leading to 1.4.3
Saturday, February 25, 2017
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- Route Adlam script to Arabic shaper.
- Misc fixes.
- New API:
  hb_font_set_face()
- Deprecate API:
  hb_graphite2_font_get_gr_font()