Log Message:
harfbuzz: update to 1.8.0.

Tuesday, June 5, 2018
====================================
- Update to Unicode 11.0.0.

Overview of changes leading to 1.7.7
Tuesday, June 5, 2018
====================================
- Lots of internal changes, but not yet exposed externally.
- All HarfBuzz objects are significantly smaller in size now.
- Sinhala: Position repha on top of post-consonant, not base.
  This better matches Windows 10 behavior, which was changed
  from previous Windows versions.
- New build options:
  o New cpp macro HB_NO_ATEXIT
  o New cpp macro HB_SUBSET_BUILTIN
- Significant libharfbuzz-subset changes. API subject to change.
- New API in libharfbuzz:

+hb_blob_create_from_file()
+hb_face_count()

A hashmap implementation:
+hb-map.h
+HB_MAP_VALUE_INVALID
+hb_map_t
+hb_map_create()
+hb_map_get_empty()
+hb_map_reference()
+hb_map_destroy()
+hb_map_set_user_data()
+hb_map_get_user_data()
+hb_map_allocation_successful()
+hb_map_clear()
+hb_map_is_empty()
+hb_map_get_population()
+hb_map_set()
+hb_map_get()
+hb_map_del()
+hb_map_has()