documentation that negative strength values are possible.
Give an example call.
* include/freetype/freetype.h (FT_GlyphSlotRec): Improve
documentation of `outline' field.
* src/sfnt/sfobjc.s: Inckude FT_INTERNAL_DEBUG_H.
* src/sfnt/sfdriver.c: Include ttmtx.h.
* src/autofit/afcjk.c: Include aftypes.h and aflatin.h.