Abstract out the "print a human readable list of all the
valid log categories" functionality which is currently duplicated
in three separate places. (We leave the monitor.c help_cmd()
implementation as-is since it wants to send the message to
the monitor and add its own information.)
Signed-off-by: NPeter Maydell <peter.maydell@linaro.org>
Reviewed-by: NAndreas Färber <afaerber@suse.de>
Signed-off-by: NBlue Swirl <blauwirbel@gmail.com>