Exclude debug info for `Release' versions to reduce library size.
* src/base/ftobjs.c (FT_Open_Face): Make it work as documented, this
is, ignore `aface' completely if face_index < 0. Reported by David
Osborn <spam@habitualhiatus.com>.
* include/freetype/ftimage.h (FT_Outline_MoveToFunc,
FT_Outline_LineTo_Func, FT_Outline_ConicToFunc,
FT_Outline_CubicToFunc), src/smooth/ftgrays.c (gray_render_conic,
gray_render_cubic, gray_move_to, gray_line_to, gray_conic_to,
gray_cubic_to, gray_render_span, gray_sweep): Decorate parameters
with `const' where appropriate.