Log Message:
Updated harfbuzz to 1.5.0.

Overview of changes leading to 1.5.0
Wednesday, August 23, 2017
====================================

- Misc new API, for appending a buffer to another, and for comparing
  contents of two buffers for types of differences.

- New "unsafe-to-break" API.  Can be used to speed up reshaping
  in line-breaking situations.  Essentially, after shaping, it returns
  positions in the input string (some of the cluster boundaries) that
  are "safe to break" in that if the text is segmented at that position
  and two sides reshaped and concatenated, the shaping result is
  exactly the same as shaping the text in one piece.

  hb-view and hb-shape and hb-shape now take --verify, which verifies
  the above property.

  Some corner cases of the implementation are still not quite working.
  Those will be fixed in subsequent releases.

- New API:

hb_buffer_append()

hb_glyph_flags_t
HB_GLYPH_FLAG_UNSAFE_TO_BREAK
HB_GLYPH_FLAG_DEFINED
hb_glyph_info_get_glyph_flags()

HB_BUFFER_SERIALIZE_FLAG_GLYPH_FLAGS

hb_buffer_diff_flags_t
HB_BUFFER_DIFF_FLAG_EQUAL
HB_BUFFER_DIFF_FLAG_CONTENT_TYPE_MISMATCH
HB_BUFFER_DIFF_FLAG_LENGTH_MISMATCH
HB_BUFFER_DIFF_FLAG_NOTDEF_PRESENT
HB_BUFFER_DIFF_FLAG_DOTTED_CIRCLE_PRESENT
HB_BUFFER_DIFF_FLAG_CODEPOINT_MISMATCH
HB_BUFFER_DIFF_FLAG_CLUSTER_MISMATCH
HB_BUFFER_DIFF_FLAG_GLYPH_FLAGS_MISMATCH
HB_BUFFER_DIFF_FLAG_POSITION_MISMATCH
hb_buffer_diff