cmake HAVE_CAMV4L examples

plumonito/dtslam 3rdparty/opencv-git/cmake/OpenCVFindLibsVideo.cmake :159 

CHECK_INCLUDE_FILE(linux/videodev.h HAVE_CAMV4L)

plumonito/dtslam 3rdparty/opencv-git/modules/videoio/CMakeLists.txt :74 

elseif(HAVE_CAMV4L OR HAVE_CAMV4L2 OR HAVE_VIDEOIO)