> Why is the test program expecting to use snprintf & vsnprintf?
Probably because the test program is using libpcap (which, given that
it's testing for the existence of libpcap, it has to do), and the
version of libpcap on your system is expecting to use snprintf and
vsnprintf - the most recent versions of libpcap do.
Unfortunately, it appears your OS doesn't have snprintf or vsnprintf.
tcpdump compensates for this by supplying its own versions of those
routines, as does Ethereal; unfortunately, this doesn't help in autoconf
scripts.
I'd suggest mailing tcpdump-workers@xxxxxxxxxxx about this, as it's
really a libpcap problem, and could conceivably show up with *other*
libpcap-based programs (although Ethereal is somewhat special in that it
can be built even if you don't have libpcap - the build produces a
program that can't capture traffic, but that *can* read captures from
other programs such as tcpdump.
As a short-term fix, I would suggest either
1) upgrading your OS to a version that includes snprintf and
vsnprintf;
2) getting rid of the libpcap under "/usr/users21/toy" (and if
that's the only one installed on your system, installing an
older one that doesn't use snprintf or vsnprintf - 0.5.2
*might* not use it:
http://www.tcpdump.org/release/
).