remove support of Video4Linux1 API

the last kernel that allowed compiling this code was 2.6.37 which was
released almost 5 Years ago. So probably it does not get much testing
any more. Furthermore even back then one was better off using the V4L2
API.

The only change touching currently used code is the removal of the
global V4L2_SUPPORT variable.

modules/videoio/CMakeLists.txt

@@ -101,7 +101,7 @@ endif(HAVE_UNICAP)
 
 if(HAVE_LIBV4L)
   list(APPEND videoio_srcs ${CMAKE_CURRENT_LIST_DIR}/src/cap_libv4l.cpp)
-elseif(HAVE_CAMV4L OR HAVE_CAMV4L2 OR HAVE_VIDEOIO)
+elseif(HAVE_CAMV4L2 OR HAVE_VIDEOIO)
   list(APPEND videoio_srcs ${CMAKE_CURRENT_LIST_DIR}/src/cap_v4l.cpp)
 endif()