enable c++11 for opencv4, closes 601
enable c++11 for opencv4, closes 601

Signed-off-by: Yurii Kolesnykov <dc76e9f0c0006e8f919e0c515c66dbba3982f785@yurikoles.com>

j-b-m/mlt,j-b-m/mlt,mltframework/mlt,mltframework/mlt,j-b-m/mlt,mltframework/mlt,mltframework/mlt,j-b-m/mlt,mltframework/mlt,j-b-m/mlt,j-b-m/mlt,j-b-m/mlt,mltframework/mlt,j-b-m/mlt,j-b-m/mlt,j-b-m/mlt,mltframework/mlt,mltframework/mlt,mltframework/mlt,mltframework/mlt