Wrap Vararg Functions

In my mind to wrap a vararg function I have to call its corresponding v-function (e.g. printf and vprintf). For those functions that do not have such counterparts, I intended to use Zhenyu's assembly code to inspect the stack. Last weekend when looking into cURL's source code, I found out that using the va_arg macro and passing the resulting pointer directly to vararg functions worked quite well. It's so easy! Phew!