fix SYSROOT setting for cross compiling

CMakeLists.txt

@@ -35,7 +35,7 @@ include_directories("v4l2wrapper/inc")
 find_library(V4L2WRAPPER_LIBRARY libv4l2wrapper.a PATHS "." NO_CMAKE_FIND_ROOT_PATH)
 if (NOT V4L2WRAPPER_LIBRARY)
         message(STATUS "Installing v4l2wrapper")
-        EXEC_PROGRAM("git submodule init && git submodule update && make -C v4l2wrapper CC=${CMAKE_C_COMPILER} CFLAGS_EXTRA=--sysroot=${CMAKE_FIND_ROOT_PATH} && cp v4l2wrapper/libv4l2wrapper.a . && make -C v4l2wrapper clean")
+        EXEC_PROGRAM("git submodule init && git submodule update && make -C v4l2wrapper CC=${CMAKE_C_COMPILER} SYSROOT=${CMAKE_FIND_ROOT_PATH} && cp v4l2wrapper/libv4l2wrapper.a . && make -C v4l2wrapper clean")
 	find_library(V4L2WRAPPER_LIBRARY libv4l2wrapper.a PATHS "." NO_CMAKE_FIND_ROOT_PATH)
         message(STATUS "v4l2wrapper built in V4L2WRAPPER_LIBRARY=${V4L2WRAPPER_LIBRARY}")	
 endif (NOT V4L2WRAPPER_LIBRARY)