support setting focus and autofocus with V4L2

also refactor property range handling and opencv property to V4L2
translation.

modules/videoio/include/opencv2/videoio.hpp

@@ -133,7 +133,9 @@ enum { CAP_PROP_POS_MSEC       =0,
        CAP_PROP_TILT          =34,
        CAP_PROP_ROLL          =35,
        CAP_PROP_IRIS          =36,
-       CAP_PROP_SETTINGS      =37
+       CAP_PROP_SETTINGS      =37,
+       CAP_PROP_BUFFERSIZE    =38,
+       CAP_PROP_AUTOFOCUS     =39
      };
 
 

modules/videoio/include/opencv2/videoio/videoio_c.h

@@ -189,6 +189,7 @@ enum
     CV_CAP_PROP_IRIS          =36,
     CV_CAP_PROP_SETTINGS      =37,
     CV_CAP_PROP_BUFFERSIZE    =38,
+    CV_CAP_PROP_AUTOFOCUS     =39,
 
     CV_CAP_PROP_AUTOGRAB      =1024, // property for videoio class CvCapture_Android only
     CV_CAP_PROP_SUPPORTED_PREVIEW_SIZES_STRING=1025, // readonly, tricky property, returns cpnst char* indeed