Until version 4.1 ISC DHCP was using its own library libdst for authentication of DHCP Messages (RFC 3118). This library implements HMAC-MD5 (RFC 2104). Since 4.2 libdns from ISC BIND has been used for this purpose. On Fedora we ship libdns with bind-libs-lite package. There's been no reason to ship libdst with dhcp-libs anymore. Although I'm not sure why upstream still includes the code with DHCP and builds libdst by default it should be quite easy to remove it because nothing has been linking against it anymore.
Shawn Routhier's (ISC) response: As I recall I left those directories in place in case somebody was using them to build their own program. For example if somebody had been constructing something similar to OMSHELL. While I don't know of anybody doing so, it seemed harmless to continue including the code.
dhcp-4.2.4-15.P2.fc18 has been submitted as an update for Fedora 18. https://admin.fedoraproject.org/updates/dhcp-4.2.4-15.P2.fc18
dhcp-4.2.4-15.P2.fc18 has been pushed to the Fedora 18 stable repository. If problems still persist, please make note of it in this bug report.