cmake HAVE_DAG_VDAG examples

asset-group/5ghoul-5g-nr-attacks libs/libpcap/CMakeLists.txt :1761 

check_library_exists(vdag vdag_set_device_info ${DAG_LIBRARY_DIR}
                           HAVE_DAG_VDAG)

CTSRD-CHERI/cheribsd contrib/libpcap/CMakeLists.txt :2580 

check_library_exists(vdag vdag_set_device_info ${DAG_LIBRARY_DIR} HAVE_DAG_VDAG)