undo comment unused variable in spline.cpp
undo comment unused variable in spline.cpp

chdinh/mne-cpp,chdinh/mne-cpp,chdinh/mne-cpp,mne-tools/mne-cpp,mne-tools/mne-cpp,chdinh/mne-cpp,mne-tools/mne-cpp,chdinh/mne-cpp,mne-tools/mne-cpp,mne-tools/mne-cpp,chdinh/mne-cpp,mne-tools/mne-cpp