Log Message:
harfbuzz: update to 1.7.1.

Overview of changes leading to 1.7.1
Tuesday, November 14, 2017
====================================

- Fix atexit object destruction regression.
- Fix minor integer-overflow.

Overview of changes leading to 1.7.0
Monday, November 13, 2017
====================================

- Minor Indic fixes.
- Implement kerning and glyph names in hb-ot-font.
- Various DSO optimization re .data and .bss sizes.
- Make C++11 optional; build fixes.
- Mark all other backends "unsafe-to-break".
- Graphite fix.

Overview of changes leading to 1.6.3
Thursday, October 26th, 2017
====================================

- Fix hb_set_t some more.  Should be solid now.
- Implement get_glyph_name() for hb-ot-font.
- Misc fixes.

Overview of changes leading to 1.6.2
Monday, October 23nd, 2017
====================================

- Yesterday's release had a bad crasher; don't use it.  That's what
  happens when one works on Sunday...
  https://github.com/behdad/harfbuzz/issues/578
- Build fixes for FreeBSD and Chrome Android.

Overview of changes leading to 1.6.1
Sunday, October 22nd, 2017
====================================

- Don't skip over COMBINING GRAPHEME JOINER when ligating, etc.
  To be refined: https://github.com/behdad/harfbuzz/issues/554
- Faster hb_set_t implementation.
- Don't use deprecated ICU API.
- Fix undefined-behavior in Myanmar shaper, introduced in 1.6.0
- Deprecated API:
  hb_set_invert()

Overview of changes leading to 1.6.0
Friday, October the 13th, 2017
====================================

- Update to Unicode 10.

- Various Indic and Universal Shaping Engine fixes as a result of
  HarfBuzz Hackfest with Jonathan Kew at Web Engines Hackfest at
  the Igalia offices in A Coruña, Spain.  Thanks Igalia for having
  us!

- Implement Unicode Arabic Mark Ordering Algorithm UTR#53.

- Implement optical sizing / tracking in CoreText backend, using
  new API hb_font_set_ptem().

- Allow notifying hb_font_t that underlying FT_Face changed sizing,
  using new API hb_ft_font_changed().

- More Graphite backend RTL fixes.

- Fix caching of variable font shaping plans.

- hb-view / hb-shape now accept following new arguments:

  o --unicodes: takes a list of hex numbers that represent Unicode
    codepoints.

New API:
+hb_face_get_table_tags()
+hb_font_set_ptem()
+hb_font_get_ptem()
+hb_ft_font_changed()