New warnings on linux

[acnazarejr]

/vagrant/modules/ml/src/oaa_classifier.cpp: In member function ‘virtual void ssig::OAAClassifier::learn(const cv::Mat_&, const cv::Mat_&)’:
/vagrant/modules/ml/src/oaa_classifier.cpp:85:11: warning: unused variable ‘maxThreadsN’ [-Wunused-variable]
const int maxThreadsN = omp_get_max_threads()/2;
^
/vagrant/modules/ml/src/oaa_classifier.cpp: In member function ‘virtual int ssig::OAAClassifier::predict(const cv::Mat_&, cv::Mat_&) const’:
/vagrant/modules/ml/src/oaa_classifier.cpp:113:11: warning: unused variable ‘maxThreadsN’ [-Wunused-variable]
const int maxThreadsN = omp_get_max_threads()/2;
^