optimized RGB15 and RGB16 color keyed blit (doubled performance on some cpus)
optimized RGB15 and RGB16 color keyed blit (doubled performance on some
cpus)

df_dok benchmarks (MPixel/s):

Apple PowerBook G3 400Mhz:
15.2  -> 30.8

Sony Vaio PIII 700 Mhz:
69.5 -> 112.9

PowerPC 823 66 Mhz:
2.65 -> 3.49

kaostao/directfb,kevleyski/DirectFB-1,kevleyski/DirectFB-1,kaostao/directfb,jcdubois/DirectFB,DirectFB/directfb,kevleyski/directfb,sklnet/DirectFB,dfbdok/DirectFB1,lancebaiyouview/DirectFB,djbclark/directfb-core-DirectFB,kevleyski/directfb,lancebaiyouview/DirectFB,mtsekm/test,sklnet/DirectFB,Distrotech/DirectFB,djbclark/directfb-core-DirectFB,jcdubois/DirectFB,kevleyski/DirectFB-1,deniskropp/DirectFB,djbclark/directfb-core-DirectFB,deniskropp/DirectFB,Distrotech/DirectFB,mtsekm/test,dfbdok/DirectFB1,deniskropp/DirectFB,kevleyski/directfb,DirectFB/directfb,mtsekm/test,jcdubois/DirectFB,sklnet/DirectFB,deniskropp/DirectFB,kaostao/directfb,kevleyski/directfb,lancebaiyouview/DirectFB,lancebaiyouview/DirectFB,kevleyski/DirectFB-1,djbclark/directfb-core-DirectFB,DirectFB/directfb,Distrotech/DirectFB,dfbdok/DirectFB1,sklnet/DirectFB