The existing stuff doesn't appear to work (I tried it on 32-bit Ubuntu
18.04, and it did *not* add any flags to the compilation, as it appeared
not to conclude that they were necessary, even though they were).
Pull in the stuff from libpcap, which *does* appear to work. (it does
so in my 32-bit Ubuntu testing).
This should fix#17301.
While we're at it, fix cppcheck.sh so that it doesn't attempt to run
cppcheck on files that have been deleted.
Guy Harris