cmake HAVE_PCAP_VERSION examples

boundary/wireshark cmake/modules/FindPCAP.cmake :113 

CHECK_VARIABLE_EXISTS("pcap_version" HAVE_PCAP_VERSION)

usb-tools/USBProxy-legacy src/cmake/modules/FindPCAP.cmake :104 

CHECK_VARIABLE_EXISTS("pcap_version" HAVE_PCAP_VERSION)