cmake: don't use Eigen auto-detection in cross-compiling modes
cmake: don't use Eigen auto-detection in cross-compiling modes

Sometimes it tries to use host '/usr/include' directory and garbages
compiler flags with invalid '-I /usr/include'

opencv/opencv,opencv/opencv,opencv/opencv,opencv/opencv,opencv/opencv,opencv/opencv,opencv/opencv,opencv/opencv,opencv/opencv,opencv/opencv