scale closer to other north arrows

git-svn-id: https://svn.osgeo.org/grass/grass/trunk@56824 15284696-431f-4ddb-bdfa-cd5b030d7da7

lib/symbol/symbol/n_arrows/n_arrow2

@@ -1,5 +1,5 @@
 VERSION 1.0
-BOX -3 -3 3 3
+BOX -6 -6 6 6
 POLYGON
  RING
  LINE