Bit field packing is a delicate field.  Issue reported in comment 3 here:
http://bugzilla.gnome.org/show_bug.cgi?id=591511

We were copying glyphs to output.  This should not happen when in
GPOS.  Back then it was fine, then some optimizations broke then
assumption.

2008-01-15  Behdad Esfahbod  <behdad@gnome.org>

        * pango/opentype/*:
        HarfBuzz was relicensed to a more generous and simpler license.
        Adapt.  See pango/opentype/COPYING for the new license which is
        LGPL-compatible.

2007-11-07  Behdad Esfahbod  <behdad@gnome.org>

        * pango/opentype/*: Some more cleanup and merging.

2007-10-24  Behdad Esfahbod  <behdad@gnome.org>

        * pango/opentype/*: New header file harfbuzz-global.h.  Rename
        FT_* int types to HB_* types.

2007-10-11  Behdad Esfahbod  <behdad@gnome.org>

        * pango/opentype/*: Mark internal symbols as HB_INTERNAL and
        define that to static in harfbuzz.c.

        * pango/opentype/harfbuzz-buffer-internal.h: New file.