message: copy types are now marked as is_const
diff: @@ -1680,6 +1680,7 @@ class PrimitiveTypeInfo(TypeInfo):
  self.rust_extern = self.rust_full = self.rust_local = primitive["rust_local"]
  self.rust_safe_id = self.typeid.replace(" ", "_")
  self.c_safe_id = self.cpp_extern.replace(" ", "_").replace("*", "X").replace("::", "_")
  + self.is_const = True
  def cpp_arg_func_call(self, var_name, is_output=False):
  return var_name
  @@ -1718,6 +1719,7 @@ class SimpleClassTypeInfo(TypeInfo):
  self.c_safe_id = self.cpp_extern
  self.rust_extern = self.rust_full
  self.is_trait = False
  + self.is_const = True
  def __str__(self):
  return "%s (simple)"%(self.cpptype)
  