Benchmark DirectFB

Benchmarks
The DirectFB example suites include benchmark 'df_dok'. We have ran this benchmark on the following platform:

After enabling 2D acceleration in A* environment, graphics benchmark score becomes better. BR It looks like even embedded processor like SH-4 can be used when `DirectFb` can utilize H/W drawing power through graphics libraly. So graphics libraly would be essential stuff in graphics system.