Don't store the comments in a capture_options structure, because that's
available only if we're being built with capture support, and
--capture-comment can be used in TShark when reading a capture file and
writing another capture file, with no live capture taking place.
This means we don't handle that option in capture_opts_add_opt(); handle
it in the programs that support it.
Support writing multiple comments in dumpcap when capturing.
These changes also fix builds without pcap, and makes --capture-comment
work in Wireshark when a capture is started from the command line with
-k.
Update the help messages to indicate that --capture-comment adds a
capture comment, it doesn't change any comment (much less "the" comment,
as there isn't necessarily a single comment).
Update the man pages:
- not to presume that only pcapng files support file comments (even if
that's true now, it might not be true in the future);
- to note that multiple instances of --capture-comment are supported,
and that multiple comments will be written, whether capturing or reading
one file and writing another;
- clarify that Wireshark doesn't *discard* SHB comments other than the
first one, even though it only displays the first one;
0a9ef601d2