Calling SDL_BlitSurface() on overlaping rectangles while
running on SSE3 optimized standard C library.
Rectangle bitmaps content is corrupted what produces
garbage on the screen.
Internal SDL_BlitCopyOverlap() function has been fixed to
copy bitmaps between overlapping areas correctly.
SDL_BlitSurface() function performs correctly even if
standard C library does not implement memcpy() safely for
operation on overlapping memory areas.