add missing Makefile change

Signed-off-by: Jack Wang <jinpu.wang@profitbricks.com>
Merge branch 'master' of https://github.com/xjtuwjp/EnhanceIO
minor clean up, remove debug code

Signed-off-by: Jack Wang <jinpu.wang@profitbricks.com>
Merge pull request #39 from xjtuwjp/master

minor clean up, remove debug code about random policy change