Apply 'locl' with 'ccmp' in Arabic shaper

According to Peter Constable this is indeed what Uniscribe has been
doing for years.

Mozilla Bug 667166 - wrong shape of letter when it comes at the end of
word in the arabic version of Firefox 5.0

src/hb-ot-shape-complex-arabic.cc

@@ -163,6 +163,7 @@ _hb_ot_shape_complex_collect_features_arabic (hb_ot_map_builder_t *map, const hb
    */
 
   map->add_bool_feature (HB_TAG('c','c','m','p'));
+  map->add_bool_feature (HB_TAG('l','o','c','l'));
 
   map->add_gsub_pause (NULL, NULL);