Vector Linux 4.0 (Slackware based)
gcc version 3.3.6
kernel 2.4.29
Compilation ot the source code halted with undefined references to IPV6_V6ONLY.
This fixed the problem:
I added to the top of src/network/rootwrap.c:
#ifndef IPV6_V6ONLY
# define IPV6_V6ONLY 0
#endif
Compilation then completed normally.