jmavsim_run.sh: add more aggressive GC option

This reduces memory usage by roughly 100MB on my laptop

Tools/jmavsim_run.sh

@@ -43,4 +43,12 @@ fi
 
 ant create_run_jar copy_res
 cd out/production
-java -Djava.ext.dirs= -jar jmavsim_run.jar $device $extra_args
+
+java -XX:GCTimeRatio=20 -Djava.ext.dirs= -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
+fi
+