pango-cairo backward compat

[Allin Cottrell <cottrell wfu edu>]

I'm trying to write a function in such a way that (a) it doesn't
use currently deprecated code if that's avoidable while (b) it
builds OK against earlier versions of pango. I'd be grateful if
any pango expert could take a quick look at this and see if
anything looks wrong:

PangoLayout *gp_cairo_create_layout (void)
{
    static PangoFontMap *fontmap;
    PangoContext *context;
    PangoLayout *layout;

    if (fontmap == NULL) {
        fontmap = pango_cairo_font_map_new_for_font_type(CAIRO_FONT_TYPE_FT);
        if (fontmap == NULL) {
            fontmap = pango_cairo_font_map_get_default();
        }
    }

#if PANGO_VERSION_MAJOR > 1 || PANGO_VERSION_MINOR >= 22
    context = pango_font_map_create_context(fontmap);
#else
    context = pango_cairo_font_map_create_context((PangoCairoFontMap *)
                                                  fontmap);
#endif
    layout = pango_layout_new(context);
    g_object_unref(context);

    return layout;
}

My main concern is whether the cast from PangoFontMap to
PangoCairoFontMap is kosher.

Thanks!

Allin Cottrell