Log Message:
Update harfbuzz to 1.2.0:

Overview of changes leading to 1.2.0
Friday, February 19, 2016
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- Fix various issues (hangs mostly) in case of memory allocation failure.
- Change mark zeroing types of most shapers from BY_UNICODE_LATE to
  BY_GDEF_LATE.  This seems to be what Uniscribe does.
- Change mark zeroing of USE shaper from NONE to BY_GDEF_EARLY.  That's
  what Windows does.
- Allow GPOS cursive connection on marks, and fix the interaction with
  mark attachment.  This work resulted in some changes to how mark
  attachments work.  See:
  https://github.com/behdad/harfbuzz/issues/211
  https://github.com/behdad/harfbuzz/commit/86c68c7a2c971efe8e35b1f1bd99401dc8b688d2
- Graphite2 shaper: improved negative advance handling (eg. Nastaliq).
- Add nmake-based build system for Windows.
- Minor speedup.
- Misc. improvements.