r178333 - Don't special case one line extern "C" decls.

[Rafael Espíndola]

> Where's the code that avoids warning for that case? It seems like that
> logic should be broadened, rather than needing another particular case
> added, no?

When this was written getStorageClassAsWritten would return SC_None

extern "C" const char *Version_string = "2.9";

but SC_Extern for

extern "C" {
  extern const char *Version_string2 = "2.9";
}

Since then getStorageClassAsWritten has been removed and the new
getStorageClass handles both cases uniformly.

Cheers,
Rafael