Forcing the use of a dedicated header to replace pcap.h is
unnecessary code and mental overhead in this case. We can
use config.h instead for the same purpose of defining a
macro symbol before including pcap.h.
Repeated words were found with:
egrep "(\b[a-zA-Z]+) +\1\b" . -Ir
and then manually reviewed.
Non-displayed strings (e.g., in comments)
were also corrected, to ease future review.
The distinction between the different kinds of capture utility
may not warrant a special subfolfer for each, and sometimes the
distinction is not be clear or some functions could stradle
multiple "categories" (like capture_ifinfo.[ch]).
Simplify by having only a generic 'capture' subfolder. The
separate CMake libraries are kept as a way to reuse object code
efficiently.