Make libv4l support optional for testing purposes.

CMakeLists.txt

@@ -153,6 +153,7 @@ OCV_OPTION(WITH_CSTRIPES       "Include C= support"                          OFF
 OCV_OPTION(WITH_TIFF           "Include TIFF support"                        ON   IF (NOT IOS) )
 OCV_OPTION(WITH_UNICAP         "Include Unicap support (GPL)"                OFF  IF (UNIX AND NOT APPLE AND NOT ANDROID) )
 OCV_OPTION(WITH_V4L            "Include Video 4 Linux support"               ON   IF (UNIX AND NOT ANDROID) )
+OCV_OPTION(WITH_LIBV4L         "Use libv4l for Video 4 Linux support"        ON   IF (UNIX AND NOT ANDROID) )
 OCV_OPTION(WITH_DSHOW          "Build HighGUI with DirectShow support"       ON   IF (WIN32 AND NOT ARM) )
 OCV_OPTION(WITH_MSMF           "Build HighGUI with Media Foundation support" OFF  IF WIN32 )
 OCV_OPTION(WITH_XIMEA          "Include XIMEA cameras support"               OFF  IF (NOT ANDROID AND NOT APPLE) )

cmake/OpenCVFindLibsVideo.cmake

@@ -125,7 +125,9 @@ endif(WITH_XINE)
 # --- V4L ---
 ocv_clear_vars(HAVE_LIBV4L HAVE_CAMV4L HAVE_CAMV4L2 HAVE_VIDEOIO)
 if(WITH_V4L)
-  CHECK_MODULE(libv4l1 HAVE_LIBV4L)
+  if(WITH_LIBV4L)
+    CHECK_MODULE(libv4l1 HAVE_LIBV4L)
+  endif()
   CHECK_INCLUDE_FILE(linux/videodev.h HAVE_CAMV4L)
   CHECK_INCLUDE_FILE(linux/videodev2.h HAVE_CAMV4L2)
   CHECK_INCLUDE_FILE(sys/videoio.h HAVE_VIDEOIO)