propagated fix for Matx(Matx::diag_type) constructor from branch 2.3 to trunk
propagated fix for Matx(Matx::diag_type) constructor from branch 2.3 to trunk

opencv/opencv,apavlenko/opencv,opencv/opencv,opencv/opencv,apavlenko/opencv,opencv/opencv,apavlenko/opencv,apavlenko/opencv,opencv/opencv,apavlenko/opencv,opencv/opencv,opencv/opencv,opencv/opencv,apavlenko/opencv,opencv/opencv,opencv/opencv