Fix featuretracker

Added the fix to the cmakelist as mentioned in this Q&A forum topic.
However, the fix about the default case not having a break, has already been solved in the 2.4 branch.

Topic: http://answers.opencv.org/question/19531/featuretracker-opencv-has-been-compiled-without/ 

If this is not correct, feel free to close the pull request down.