* include/freetype/freetype.h (FT_Open_Flags): Replaced with
#defines for the constants.
(FT_Open_Args): Change type of `flags' to FT_UInt.
(FT_GlyphSlot): Move `flags' to FT_Slot_Internal.

* include/freetype/ftimage.h (FT_Outline_Flags, FT_Raster_Flag):
Replaced with #defines for the constants.

* include/freetype/internal/ftobjs.h (FT_Slot_Internal): New
field `flags' (from FT_GlyphSlot).
Updated all affected source files.
(FT_GLYPH_OWN_BITMAP): New macro (from ftgloadr.h).

* include/freetype/internal/ftgloadr.h (FT_GLYPH_OWN_BITMAP): Moved
to ftobjs.h.

* src/base/ftglyph.c (FT_Glyph_To_Bitmap): Use dummy
FT_GlyphSlot_Internal object.