Ask for more information if we don't find pcap_loop.

Ask for more information if we don't find pcap_loop.

I give up.

People keep reporting that the configure process for tcpdump fails to
find pcap_loop, and the config.log file they send us says there's no
pcap_parse in libpcap, which suggests that something went wrong in the
build process for libpcap; perhaps they don't have Bison and the
configure script got confused and failed to cause the parser to be named
"pcap_parse", or something such as that, or perhaps Bison was recently
"improved" in a fashion that breaks that, but I've never been able to
reproduce this on any of the Linux distribution installations to which
*I* have access.

I therefore ask them to send the config.log output and make output for
libpcap; *not one of the reporters of this problem* has bothered to send
that information, so we're stuck.  Perhaps they don't care enough (in
which case, why did they bother asking us about it?), or perhaps they're
annoyed that we asked them a further question rather than Just Fixing
The Problem(TM) (in which case, all I have to say is "welcome to the
Wonderful World Of Computer Software(TM) - get used to it").

So let's just ask for all that information.  (I would not be surprised
if this doesn't suffice and that they *still* just send us the tcpdump
config.log output, but at least I'll be able to tell them that they
should have Read The Fine Error Message(TM).)