[autofit] Use better blue zone characters for lowercase latin.

The number of lowercase characters for computing the top flat blue
zone value was too small (in most cases only `x' and `z').  If one
of the two characters has a large serif, say, it can happen that
FreeType must select between two different values, having a 50%
chance to use the wrong one.  As a result, rendering at larger PPEM
values could yield uneven lowercase glyph heights.

Problem reported by Christoph Koeberlin <christoph@koe.berlin>.

* src/autofit/afblue.dat (AF_BLUE_STRING_LATIN_SMALL): Replaced
with...
(AF_BLUE_STRING_LATIN_SMALL_TOP, AF_BLUE_STRING_LATIN_SMALL_BOTTOM):
... New, extended sets.
(AF_BLUE_STRINGSET_LATN): Updated.

* src/autofit/afblue.c, scr/autofit/afblue.h: Regenerated.
4 files changed