The code represents a considerable maintenance burden and it is not
clear that it gives a noticeable benefit to outweigh this after 10
years of improvements in compiler technology since its creation.
Also use the resulting 16bpp functions for anything >8 and <=16, not just
9 and 10. This fixes 12 and 14bpp H264 support.
Signed-off-by: Michael Niedermayer <michaelni@gmx.at>