[cairo] RFC: converting public API to use const

[Chris Wilson]

Recently I've had the unpleasant task of having to cast calls to
cairo_font_option_status() in order to avoid the compiler warnings when
trying to call the function with a const cairo_font_options_t.

Does anyone have any objects to changing:
    cairo_status_t cairo_font_options_status (cairo_font_options_t *);
to
    cairo_status_t cairo_font_options_status (const cairo_font_options_t *);
i.e. can anyone identify a situation where this change will break the
ABI or feels it is an incompatible change in the API?
--
Chris Wilson