Tools: fix 'Assistive technology not found error'

On Ubuntu we often saw the error
Assistive technology not found AWTError when starting jMAVSim.

This should be fixed by appending this cli argument to java.

As suggested in https://github.com/PX4/containers/issues/206

Tools/jmavsim_run.sh

@@ -68,11 +68,11 @@ fi
 ant create_run_jar copy_res
 cd out/production
 
-java -XX:GCTimeRatio=20 -Djava.ext.dirs= -jar jmavsim_run.jar $device $extra_args
+java -XX:GCTimeRatio=20 -Djava.ext.dirs= -Djavax.accessibility.assistive_technologies=" " -jar jmavsim_run.jar $device $extra_args
 ret=$?
 if [ $ret -ne 0 -a $ret -ne 130 ]; then # 130 is Ctrl-C
 	# if the start of java fails, it's probably because the GC option is not
 	# understood. Try starting without it
-	java -Djava.ext.dirs= -jar jmavsim_run.jar $device $extra_args
+	java -Djava.ext.dirs= -Djavax.accessibility.assistive_technologies=" " -jar jmavsim_run.jar $device $extra_args
 fi