utils: Don't use deprecated api

Port pango-viewer to use the new
pango_fc_font_map_set_default_substitute.

utils/viewer-pangoft2.c

@@ -51,7 +51,7 @@ pangoft2_view_create (const PangoViewer *klass G_GNUC_UNUSED)
   fontmap = pango_ft2_font_map_new ();
 
   pango_ft2_font_map_set_resolution (PANGO_FT2_FONT_MAP (fontmap), opt_dpi, opt_dpi);
-  pango_ft2_font_map_set_default_substitute (PANGO_FT2_FONT_MAP (fontmap), substitute_func, NULL, NULL);
+  pango_fc_font_map_set_default_substitute (PANGO_FC_FONT_MAP (fontmap), substitute_func, NULL, NULL);
 
   return fontmap;
 }

utils/viewer-pangoxft.c

@@ -51,8 +51,8 @@ pangoxft_view_create (const PangoViewer *klass)
 
   XftInit (NULL);
 
-  pango_xft_set_default_substitute (instance->display, instance->screen,
-				    default_substitute, NULL, NULL);
+  pango_fc_font_map_set_default_substitute (PANGO_FC_FONT_MAP (pango_xft_get_font_map (instance->display, instance->screen)),
+				            default_substitute, NULL, NULL);
 
   return instance;
 }