Missing import

test.h:
```c
typedef __builtin_va_list __gnuc_va_list;
typedef __gnuc_va_list va_list;
```

test.d:
```d
extern (C):

alias __gnuc_va_list = __va_list_tag[1];
alias va_list = __va_list_tag[1];
```

 ```test.d``` is missing ```import core.stdc.stdarg;```  