(Ara) Add can_VV; make أَنْ a default c2 for VVs

src/arabic/ParadigmsAra.gf

@@ -536,7 +536,7 @@ resource ParadigmsAra = open
   mkVS  v = v ** {lock_VS = <>} ;
   mkVQ  v = v ** {lock_VQ = <>} ;
 
-  regVV : V -> VV = \v -> lin VV v ** {c2 = []} ;
+  regVV : V -> VV = \v -> lin VV v ** {c2 = "أَنْ"} ;
   c2VV : V -> Str -> VV = \v,prep -> regVV v ** {c2 = prep} ;
 
   V0 : Type = V ;