[svn r328] Fixed an issue with interfaces where the vtable type of a interface implemented could be invalid. Fixes several tango modules like, FileStream, ServerSocket and most tina cluster modules :)

module typeinfo;
extern(C) int printf(char*, ...);

void main()
{
    auto ti = typeid(int);
    char[] str = ti.toString();
    printf("%.*s\n", str.length, str.ptr);
    assert(str == "int");
}