Fix some missing (transparent) text with libsdl-1.2.15_p20210224.
Same issue as t4k-common-0.1.1 given tuxtype shares the same
code and wasn't migrated to support the separate library yet.
--- a/src/SDL_extras.c
+++ b/src/SDL_extras.c
@@ -1297,3 +1297,3 @@
   /* Use color key for eventual transparency: */
-  color_key = SDL_MapRGB(bg->format, 01, 01, 01);
+  color_key = SDL_MapRGBA(bg->format, 01, 01, 01, 0xff);
   SDL_FillRect(bg, NULL, color_key);
@@ -1344,3 +1344,3 @@
   SDL_SetColorKey(bg, SDL_SRCCOLORKEY|SDL_RLEACCEL, color_key);
-  out = SDL_DisplayFormatAlpha(bg);
+  out = SDL_DisplayFormat(bg);
   SDL_FreeSurface(bg);