Update FreeType to v. 2.8.1

CHANGES BETWEEN 2.8 and 2.8.1

  I. IMPORTANT BUG FIXES

    - B/W  hinting   of  TrueType   fonts  didn't  work   properly  if

      interpreter version 38 or 40 was selected.

    - Some severe  problems within the handling  of TrueType Variation

      Fonts were found and fixed.

    - Function `FT_Set_Var_Design_Coordinates' didn't correctly handle

      the case with less input coordinates than axes.

  II. IMPORTANT CHANGES

    - By default,  FreeType  now offers  high  quality  LCD-optimized

      output  without resorting to ClearType techniques of resolution

      tripling and filtering.  In this method,  called Harmony,  each

      color channel is generated separately  after shifting the glyph

      outline,  capitalizing on the fact  that the color grids on LCD

      panels  are  shifted  by  a third  of  a pixel.  This output is

      indistinguishable from ClearType with a light 3-tap filter.