A21: fix warning: no previous prototype for function ... [-Wmissing-prototypes]

Second try... ;-)

Remove also double space

Change-Id: I77aa269c1abae18b4fb9daec6cc0ac862cf4ab9f
Reviewed-on: https://code.wireshark.org/review/5421
Petri-Dish: Anders Broman <a.broman58@gmail.com>
Reviewed-by: Anders Broman <a.broman58@gmail.com>