Replace the only instance of sed(1) in bsdconfig(8) with awk(1).

MFC after:	3 days

usr.sbin/bsdconfig/share/keymap.subr

@@ -219,7 +219,7 @@ f_keymap_get_all()
 			echo -n "$k "
 			# NOTE: Translate '8x8' to '8x08' before sending to
 			# sort(1) so that things work out as we might expect.
-			debug= keymap_$k get desc | sed -e 's/8x8/8x08/g'
+			debug= keymap_$k get desc | awk 'gsub(/8x8/,"8x08")||1'
 		done | sort -k2 | awk '{
 			printf "%s%s", (started ? " " : ""), $1; started = 1
 		}'