shairport: remove service_stop call to SIGINT. SIGINT/SIGTERM both work in latest version.

Fixes restart/reload calls

Signed-off-by: Ted Hess <thess@kitschensync.net>

multimedia/shairport/files/shairport.init

 	config_load shairport
 	config_foreach start_instance shairport
 }
-
-stop_service() {
-	# FIXME: workaround until procd supports custom signal
-	killall -SIGINT shairport
-}