Core Text seems to apply them to Latin text, but Uniscribe doesn’t.

See https://github.com/harfbuzz/harfbuzz/pull/1908#issuecomment-521819343

Fixes https://github.com/harfbuzz/harfbuzz/issues/1907

To satisfy -valgrind and -tsan bots, very ugly

Probably we should just remove timeout when running tsan and vaglrind here, the flaky bots

* The ‘height’ needs to be negated since the API returns “distance from
  top to bottom side”.
* Similarly, the ‘y_offset‘ needs to be added to the height to get the
  ‘y_bearing’, since sbix’s offset is “the point in the glyph relative
  to its lower-left corner which corresponds to the origin” while
  ‘y_bearing’ is the “top side of glyph from origin”.

With these changes the sbix glyph metrics return values similar to other
tables, as they were otherwise unusable.

Fixes https://github.com/harfbuzz/harfbuzz/pull/1432

Now is flaky let's just increase and maybe investigate later

And enable more tests able to trig the issue.

https://github.com/harfbuzz/harfbuzz/pull/1799

add Unicode UCS-4 cmap
fix Unicode bits in OS/2
add Unicode cmap sub-table in SourceHanSans-Regular_subset.otf
regenerate cff subset test expected results

To HB_OT_MATH_GLYPH_PART_FLAG_EXTENDER.  Added a deprecated macro.

Fixes https://github.com/harfbuzz/harfbuzz/issues/1734

nothing important, fixing a copy paste error inconsistency