Seems like kdebase-runtime-4.4.5/kdesu/kdesud/secure.cpp is using ucred instead of sockpeercred from socket.h and thus will not compile. The diff to patch this follows:
--- secure.cpp.orig Thu Aug 7 10:21:07 2008 +++ secure.cpp Fri Jul 16 12:41:33 2010 @@ -34,8 +34,8 @@ SocketSecurity::SocketSecurity(int sockfd) : pid(-1), gid(-1), uid(-1) { - ucred cred; - ksocklen_t len = sizeof(struct ucred); + sockpeercred cred; + ksocklen_t len = sizeof(struct sockpeercred); if (getsockopt(sockfd, SOL_SOCKET, SO_PEERCRED, &cred, &len) < 0) { kError() << "getsockopt(SO_PEERCRED) " << perror << endl; return;