Fix a bug where ::warning() was called with a va_list argument instead of an actual vararg list. Also cleaned up the format for warnings. (Previously some would start with "warning - warning - Warning:" which was a bit redundant)

module bug75;

void func(void delegate() dg)
{
}

void main()
{
    void nested() {
    }
    //func(&nested);
    void delegate() dg = &nested;
}