Added slow but complete blit fallback

Don't try to RLE encode surfaces that have alpha channel and alpha modulation
Don't turn on blending when converting an RGB surface to RGBA format
Do turn on blending when converting colorkey to alpha channel

--HG--
extra : convert_revision : svn%3Ac70aab31-4412-0410-b14c-859654838e24/trunk%403285

src/video/SDL_RLEaccel.c

@@ -1819,6 +1819,7 @@ SDL_RLESurface(SDL_Surface * surface)
 
     /* Pass on combinations not supported */
     if ((flags & SDL_COPY_MODULATE_COLOR) ||
+        ((flags & SDL_COPY_MODULATE_ALPHA) && surface->format->Amask) ||
         (flags & (SDL_COPY_ADD | SDL_COPY_MOD)) ||
         (flags & SDL_COPY_NEAREST)) {
         return -1;