cmake HAVE_SYS_DLPI_EXT_H examples

asset-group/5ghoul-5g-nr-attacks libs/libpcap/CMakeLists.txt :1262 

check_include_file(sys/dlpi_ext.h HAVE_SYS_DLPI_EXT_H)

CTSRD-CHERI/cheribsd contrib/libpcap/CMakeLists.txt :1986 

check_include_file(sys/dlpi_ext.h HAVE_SYS_DLPI_EXT_H)