Since libpcap is a package in Fedora Core, an "alternative version" would be a replacement for the Core package and hence does not fit into the definition of Fedora Extras. It would fit into the definition of Fedora Alternatives [1] or any similar sub-project which may be opened in the future.
Ok thanks for the info. From that I should make the SNORT and other tools compiled against the normal pcap if they should be in extras.